PAINT   TECHNOLOGY   AND   TESTS 


Published   by  the 

McGrow-HIII   Book.  Company 

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>Succe.s.sor.s  to  the  Book  Departments  of  tKe 

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PAINT  TECHNOLOGY 
AND  TESTS- 


BY 

HENRY  A.  GARDNER 

Assistant  Director,  The  Institute  of  Industrial  Research, 

Washington,  D.  C. 

Director,  Scientific  Section,  Paint  Manufacturers'  Association 
of  the  United  States,  etc. 


McGRAW-HILL  BOOK  COMPANY 

239  WEST  39TH  STREET,  NEW  YORK 
6  BOUVERIE   STREET,  LONDON,  E.G. 

1911 


Copyright,  1911,  by  the  McGRAW-HiLL  BOOK  COMPANY 


<•? 


THE-PLIMPTON-PRESS-NORWOOD-MASS-U-S- 


TO 

MY  MOTHER 


235535 


PREFACE 

A  FEW  years  ago  the  producer  and  consumer  of  paints  pos- 
sessed comparatively  little  knowledge  of  the  relative  durability 
of  various  pigments  and  oils.  There  existed  in  some  cases  a 
prejudice  for  a  few  standard  products,  that  often  held  the  user 
in  bondage,  discouraging  investigation  and  exciting  suspicion 
whenever  discoveries  were  made,  that  brought  forth  new  ma- 
terials. Such  conditions  indicated  to  the  more  progressive,  the 
need  of  positive  information  regarding  the  value  of  various 
painting  materials,  and  the  advisability  of  having  the  questions 
at  issue  determined  in  a  practical  manner. 

The  desire  that  such  work  should  be  instituted,  resulted  in 
the  creation  of  a  Scientific  Section,  the  scope  of  which  was  to 
make  investigations  to  determine  the  relative  merits  of  different 
types  of  paint,  and  to  enlighten  the  industry  on  various  technical 
problems.  Paint  exposure  tests  of  an  extensive  nature  were 
started  in  various  sections  of  the  country  where  climatic  condi- 
tions vary.  This  field  work  was  supplemented  in  the  laboratory 
by  a  series  of  important  researches  into  the  properties  of  pig- 
ments, oils,  and  other  raw  products  entering  into  the  manufac- 
ture of  protective  coatings.  The  results  of  the  work  were 
published  in  bulletin  form  and  given  wide  distribution.  The 
demand  for  these  bulletins  early  exhausted  the  original  impress, 
and  a  general  summary  therefore  forms  a  part  of  this  volume. 

The  purpose  of  the  book  is  primarily  to  serve  as  a  reference 
\\ork  for  grinders,  painters,  engineers,  and  students;  matter  of 
an  important  nature  to  each  being  presented.  Without  repeti- 
tion of  the  matter  found  in  other  books,  two  chapters  on  raw 
products  have  been  included,  and  they  present  in  condensed 
form  a  summary  of  information  that  will  prove  of  aid  to  one 
who  desires  to  become  conversant  with  painting  materials  with 
a  view  to  continuing  tests  such  as  are  outlined  herein.  In 
other  chapters  there  has  been  compiled  considerable  matter  from 
lectures  and  technical  articles  presented  by  the  writer  before 
various  colleges,  engineering  societies,  and  painters'  associations. 


viii  PREFACE 

The  writer  wishes  to  gratefully  acknowledge  the  untiring 
efforts  of  the  members  of  the  Educational  Bureau  of  the  Paint 
Manufacturers'  Association,  whose  early  endeavors  made  possible 
many  of  the  tests  described  in  this  volume.  Kind  acknowledg- 
ment is  also  made  to  members  of  the  International  Association 
of  Master  House  Painters  and  Decorators  of  the  United  States 
and  Canada,  who  stood  always  ready  to  aid  in  investigations 
which  promised  to  bring  new  light  into  their  art  and  craft. 

HENRY  A.  GARDNER. 
WASHINGTON,  October,  1911. 


CONTENTS 


CHAPTER  PAGE 

I    PAINT  OILS  AND  THINNERS 1 

II    A  STUDY  OF  DRIERS  AND  THEIR  EFFECT 21 

III  PAINT  PIGMENTS  AND  THEIR  PROPERTIES 42 

IV  PHYSICAL  LABORATORY  PAINT  TESTS 70 

V  THE  THEORY  AND  PRACTISE  OF  SCIENTIFIC  PAINT  MAKING     .  93 

VI    THE  SCOPE  OF  PRACTICAL  PAINT  TESTS 105 

VII    CONDITIONS  NOTED  AT  INSPECTION  OF  TESTS 114 

VIII    RESULTS  OF  ATLANTIC  CITY  TESTS 124 

IX    RESULTS  OF  PITTSBURG  TESTS 135 

X  A  LABORATORY  STUDY  OF  TEST  PANELS     .     .     .     .     .     .     .  149 

XI  ADDITIONAL  TESTS  AT  ATLANTIC  CITY  AND  PITTSBURG  .     .     .  174 

XII    NORTH  DAKOTA  PAINT  TESTS 182 

XIII  TENNESSEE  PAINT  TESTS 201 

XIV  WASHINGTON  PAINT  TESTS 207 

XV    CEMENT  AND  CONCRETE  PAINT  TESTS 214 

XVI    STRUCTURAL  STEEL  PAINT  TESTS 220 

XVII  THE  SANITARY  VALUE  OF  WALL  PAINTS  252 


PAIXT   TECHNOLOGY 

CHAPTER    I 
PAINT   OILS  AND   THINNERS 

Constants  and  Characteristics  of  Oils  and  Their  Effect  upon 

Drying.  An  attempt  has  been  made  to  give  in  this  chapter  a  brief 
summary  of  the  most  important  characteristics  of  those  oils 
finding  application  in  the  paint  and  varnish  industry.  For 
methods  of  oil  analysis,  the  reader  is  referred  to  standard  works 
on  this  subject;  the  analytical  constants  herein  being  given  only 
for  comparative  purposes. 

It  is  well  known  that  one  of  the  most  desirable  features  of  a 
paint  oil  is  the  ability  to  set  up  in  a  short  period  to  a  hard 
surface  that  will  not  take  dust.  This  drying  property  is  depend- 
ent upon  the  chemical  nature  of  the  oil.  If  it  is  an  unsaturated 
compound,  like  linseed  oil,  rapid  absorption  of  oxygen  will  cause 
the  film  to  dry  rapidly  and  become  hard.  If  the  oil  be  of  a 
fully  satisfied  nature,  like  mineral  oil,  oxygen  cannot  be  taken 
up  to  any  great  extent  and  drying  will  not  take  place.  The 
various  animal  and  vegetable  oils  differ  in  their  power  of  oxygen 
absorption  to  a  lesser  or  greater  extent.  This  difference  is  referred 
to  by  the  chemist  in  terms  of  the  iodine  value.  The  iodine  value 
of  linseed  oil  is  approximately  190,  meaning  that  one  gram  of 
the  oil  will  take  up  190  centigrams  of  iodine.  Oils  with  high 
iodine  values  have  good  drying  powers,  while  those  with  low 
iodine  values  are,  as  a  rule,  very  slow  drying  in  nature. 

For  a  description  of  the  working  and  drying  properties  of  various 
oils  used  in  paints,  see  Chapter  XIV.  The  oxygen  absorption  of 
various  oils  and  mixtures  is  shown  in  Chapter  II. 

Linseed  Oil.  The  seed  of  the  flax  plant  which  is  extensively 
grown  in  North  Dakota,  Argentine  Republic  and  Russia,  con- 
tains approximately  36%  of  oil  which  may  be  obtained  by  grind- 
ing, heating,  and  expression.  Ripe  native  seed  generally  produces 

1 


2""' 


TECHNOLOGY  AND   TESTS 


a  pale  oil  of  little  odor;  the  oil  from  Argentine  seed  often  having 
a  greenish  tint  and  an  odor  resembling  sorghum.  While  filter- 
ing, pressing  and  ageing  will  remove  considerable  of  the  ("foots") 
mucilaginous  matter,  phosphates,  silica,  etc.,  from  the  oil,  the 
better  grades  which  are  intended  for  varnish  making  are  often 
refined  with  sulphuric  acid.  A  light  colored  oil  which  may  be 
heated  without  "  breaking "  results  from  this  treatment,  but 
such  oils  are  apt  to  contain  considerable  free  fatty  acid,  unless 
they  are  washed  with  alkali  subsequent  to  the  sulphuric  acid 
treatment.  On  account  of  its  rapid  drying  properties  and  general 
adaptability  for  all  classes  of  paints  and  varnishes,  linseed  oil 
has  never  been  supplanted  by  any  other  oil.  Chemically  it 


Field  of  Flax  in  bloom  in  North  Dakota 


consists  of  the  glycerides  of  linoleic,  oleic,  and  isolinoleic  acid, 
its  constitution  being  responsible  for  its  very  high  iodine  value. 

Boiled  linseed  oil,  a  heavier  and  darker  product,  is  made  by 
heating  the  raw  oil  in  open  kettles  to  high  temperatures,  generally 
with  the  addition  of  metallic  driers  such  as  litharge,  and  black 
manganese.  The  resinates  of  lead  and  manganese  are  often 
added  to  oil  heated  at  a  lower  temperature,  to  obtain  a  boiled  oil 
of  lighter  color. 

By  blowing  air  through  linseed  oil  that  has  been  heated  to 
approximately  200  degrees  Fahrenheit,  either  with  or  without 
drier,  heavy  bodied  oils  are  obtained,  which  find  special  applica- 
tion in  varnishes  and  technical  paints.  As  the  viscosity  of  these 
oils  increase,  the  iodine  values  decrease,  and  a  slight  rise  in 


New  type  of  Flax  Harvester  which  pulls  plant  up 
by  the  roots,  thus  preventing  infection  of  soil 


Modern  Concrete  Elevators  for  storing  Flaxseed 


PAINT   TECHNOLOGY  AND   TESTS 


View  of  Linseed  Oil  Factory  showing  hydraulic  press,  tanks,  etc. 


Photographs  courtesy  of  Spencer  Kellogg  Sons 

Flaxseed  Crushers 


PAINT  OILS   AND   THINNERS 


Filter  Presses  for  removing  extraneous  matter  from  linseed  oil 


Linseed  Cake  from  Oil  Press 


PAINT  TECHNOLOGY  AND   TESTS 


Glycine  Hispida 
Mammoth  soya  bean  plants 


Photographs  courtesy  of  David  Fairchild,  Plant  Explorer,  V.  S.  Dept.  of 
Agriculture 

Glycine  Hispida 
Soya  bean  plants  under  cultivation  at  Arlington,  Va. 


PAINT  OILS  AND   THINNERS 


saponification  value  and  specific  gravity  is  observed.  The  follow- 
ing analyses  of  various  types\of  linseed  oil  were  recently  made 
by  the  writer: 


Pure  Raw 
Linseed  Oil 

Boiled 
L.  O. 

(Linoleate) 

Boiled  L.  O. 
(Resinate) 

Blown 
L.  0. 

Litho. 
L.  O. 

Old 
Treated 
Oil 

Color 

Amber 

Dark 

Reddish 

Pale 

Dark 

Amber 

Clear 

Brown 

Brown 

Brown 

Clear 

Sp.  Gr.  at  15°  C. 

.933 

.941 

.930 

.968 

.970 

.943 

Average 

Iodine  No  

180 

172 

176 

13S 

102 

172 

Saponification  No.    . 

191 

187 

186 

189 

199 

197 

Free  Fatty  Acid  .  .  . 
Unsaponifiable 

3.2 
1.4 

2.7 

2.2 

2.8 

2.7 

6.9 
1.8 

Maumene 

111 









96 

Moisture 

.2% 







t 

none 

Soya  Bean  Oil.     The  soya  plant  which  is  extensively  cultivated 
in  Asia  produces  a  seed  bearing  up  to  22%  and  over  of  a  golden 


Glycine  Hispida 
Mammoth  soya  bean  plant 


Glycine  Hispida 

Soya  bean  plant,  showing  nitrogen 
gathering  tubercles  on  roots 


colored  oil  having  a  peculiar  leguminous  odor.     The  oil,  which 
probably  consists  of  the  glycerides  of  oleic,  linoleic,  and  palmitic 


8 


PAINT  TECHNOLOGY  AND   TESTS 


acids,  is  secured  by  crushing,  steaming  and  pressing  the  seed. 
There  are  several  varieties  of  the  plant,  and  they  are  said  to  be 
the  best  annual  legume  for  forage,  the  straw  and  fruit  being  rich 
in  nitrogen  and  very  fattening  as  a  cattle  food.  Soya  may  be 
grown  in  nearly  any  country  and  is  a  great  carrier  of  nitrogen 
to  land  deficient  in  this  element.  Although  the  oil  has  been 
used  abroad  for  many  years  for  soap-making  purposes,  its  use  as 
a  drying  oil  is  comparatively  recent;  being  introduced  into  the 
paint  industry  of  the  United  States  during  the  year  1909,  when 
linseed  oil  started  on  its  phenomenal  rise  in  price. 

The  oil  has  given  fair  service  in  some  paints  when  mixed  with 
upwards  of  75%  of  pure  linseed  oil.  It  is  of  a  semi-drying  nature, 
but  may  be  made  to  dry  rapidly  when  mixed  with  manganese 
and  lead  linoleate  driers.  By  compounding  it  under  heat  with 
tung  oil  and  rosin,  a  substitute  for  linseed  oil  is  produced,  which 
some  claim  to  be  quite  valuable. 

Table  I  gives  the  constants  of  several  samples  of  soya  oil  examined  by  the 
writer.  Table  II  shows  the  iodine  value  of  mixtures  of  soya  and  linseed  oils. 
Table  III  shows  the  results  of  drying  experiments  on  soya  oils  containing 
different  percentages  of  lead  and  manganese  driers. 

TABLE   I 
CHEMICAL  CHARACTERISTICS  OF  SOYA  BEAN  OIL 


Sample  No. 

Specific  gravity 

Acid  No. 

Saponification 
No. 

Iodine  No. 

Per  cent,  of 
foots 

1      .  . 

0.9233 

1.87 

188.4 

127.8 

3.81 

2   

0.9240 

1.92 

188.3 

127.2 

3  

0.9231 

1.90 

187.8 

131.7 

— 

4  

0.9233 

1.91 

188.4 

129.8 

— 

5  

— 

— 

— 

130.0 

— 

6  

— 

— 

— 

132.6 

— 

7  



— 

— 

136.0 

— 

Average  .  . 

0.9234 

1.90 

188.2 

130.7 

— 

TABLE   II 
IODINE  VALUES  OF  LINSEED  OIL  AND  MIXED  OILS 


Sample  No. 

Straight  linseed 

Soya 
25  per  cent. 
Linseed 
75  per  cent. 

Soya 
50  per  cent. 
Linseed 
50  per  cent. 

Soya 
75  per  cent. 
Linseed 
25  per  cent. 

1 

190.3 

175.2 

160.7 

140.4 

2    ... 

189.5 

175.9 

161.7 

140.8 

3    

188.0 

175.4 

160.3 

139.0 

Average    .... 

189.3 

175.5 

160.9 

140.4 

PAINT  OILS  AND  THINNERS 


TABLE  III 
SOYA  BEAN  OIL  AND  LEAD  DRIER 


Per  cent. 
PbO 

0.05 

0.10 

0.30 

0.50 

0.70 

1.00 

1.30 

1.60 

1  day 



0.07 

0.63 

1.34 

1.05 

1.53 

0.93 

1.35 

3  days 

— 

0.07 

3.52 

4.31 

2.75 

4.86 

4.82 

4.12 

Per  ct.  gain 

5  days 

— 

0.09 

5.04 

6.06 

6.09 

6.75 

6.66 

5.52 

12  days     .  . 

— 

— 

6.88 

7.54 

7.43 

7.76 

7.32 

6.47 

15  days     .  . 

— 

— 

8.84 

8.93 

8.59 

8.81 

8.44 

7.46 

20  days     .  . 

0.05 

0.20 

9.02 

9.08 

8.90 

9.03 

8.65 

7.83 

SOYA  BEAN  OIL  AND  MANGANESE  DRIER 


Per  cent.  MnOz 

0.01 

0.05 

0.15 

0.26              0.30 

f    1  day     



_ 

0.02 

0.02          0.01 

Per  ct.  gain 

•I  10  days    

— 

5.06 

6.48 

6.10          5.97 

1  20  days    

0.05 

9.07 

8.80 

6.78          6.51 

SOYA  BEAN  OIL,  MANGANESE  AND  LEAD  DRIER 


Per  cent.  PbO 

0.20 

0.30 

0.50 

MnOz 

0.05 

0.15 

0.25 

Per  ct  gain 

f    Iday     ......... 
•i    8  days    . 

3.04 
5.96 

3.77 
6.43 

3.74 

647 

12  days    . 

6.33 

6.78 

6.67 

Tung  Oil.  There  are  grown  in  China  and  Japan  many 
varieties  of  the  "  aleurites  cordata,"  popularly  known  as  the 
tung  tree.  This  tree  bears  great  quantities  of  large  sized  nuts 
containing  as  high  as  40%  of  an  oil  which  yields  itself  in  a  vis- 
cous yellow  form  upon  heating  and  crushing  of  the  fruit.  The 
raw  oil,  which  chemically  consists  of  the  glycerides  of  oleic,  oleo- 
margaric,  and  probably  isomeric  acids,  is  distinguished  by  its 
rapid  drying  properties.  When  spread  in  a  thin  layer  it  pro- 
duces a  hard  film  with  an  opaque  frosted  surface,  often  showing 
a  tendency  to  wrinkle.  Treated  tung  oil  will  dry  to  a  clear, 
water-shedding,  elastic  film.  This  oil  is  made  by  heating  the  raw 
tung  oil  at  a  comparatively  low  temperature  with  other  oils  and 
a  metallic  drier  such  as  litharge. 

The  affinity  of  tung  oil  for  rosin  has  resulted  in  the  production 
of  a  series  of  moderate-priced  varnishes  most  suitable  for  use  in 


10 


PAINT   TECHNOLOGY  AND   TESTS 


Photographs  courtesy  of  David  Fairchild 

Aleurites  Cordata  (Chinese  Wood  Oil) 
Barrel  Factory  at  Cooperage  Shop 


Photographs  courtesy  of  David  Fairchild 

Aleurites  Fordii  (Chinese  Wood  Oil) 
Fruit  from  trees  at  the  end  of  fourth  year 


PAINT  OILS  AND   THINNERS 


11 


floor  and  deck  paints  or  wherever  great  hardness  is  required. 
These  varnishes  are  also  finding  application  in  the  manufacture 
of  concrete,  steel,  and  flat  wall  paints;  being  especially  suitable 
for  the  above  purposes  when  compounded  with  kauri  gum  japan. 
During  the  boiling  of  raw  tung  oil  the  temperature  must  not 
exceed  much  over  400  degrees  Fahrenheit.  Otherwise  a  peculiar 
"  hamming  "  will  take  place,  the  whole  mass  becoming  solid  and 
of  no  further  value  as  a  varnish  or  paint  vehicle.  Some  peculiar 


Aleurites  Cordata 
Aleurites  Fordii  Wood  Oil  tree  at  Riverside,  Cali- 

Flowering  specimen  of  the  Chinese  forma,  planted  in  1907.     Photo- 

Wood  Oil  tree,  thirty  feet  high  graph  taken  in   1910,  when  tree 

and  three  feet  in  diameter,  on  had  borne  fifty  fruits 

banks  of  Yangtse  River,  Western 
Szechuan,  China.  Opium  Poppy 
in  the  foreground 

internal  disturbance  or  rearrangement  of  the  molecules  is  evi- 
dently effected  by  heat,  and  although  the  reaction  is  not  clearly 
understood,  it  has  been  ascribed  to  auto-polymerization.  Scott 
has  stated  that  the  phenomenon  of  gelatinization  is  due  to  the 
exposure  of  the  surface  of  the  oil  to  the  air,  and  that  boiling  in 
vacuo  obviates  such  results.  The  lusterless  surface  produced  when 
tung  oil  varnishes  are  dried  in  vitiated  air  would  tend  to  confirm 
the  conclusion  that  the  oil  is  very  subject  to  atmospheric  influences. 


12 


PAINT  TECHNOLOGY  AND  TESTS 


Lumbang  Oil,  which  is  obtained  from  a  tropical  species  of 
Tung,  is  very  similar  in  appearance  and  properties  to  Linseed 

CONSTANTS  OF  TUNG  OILS 


Sp.  Gr. 

Iodine  No. 

Saponifi- 
cation  No. 

Acid  No. 

No.  1.. 
No.  2 

.944 
940 

166 

164 

188 

18/1 

3.6 

.0 

Menhaden  Oil.  Of  all  the  marine-animal  oils,  such  as  seal, 
herring,  sardine,  whale,  and  menhaden,  the  latter  is  the  most 
valuable.  It  is  produced  by  steam  digestion  and  pressure  of  the 


Photographs  courtesy  Alpin  I.  Dunn 

Menhaden  Net  drying  in  the  Sun 

menhaden  or  "  piogey  "  fish,  which  are  caught  in  great  quantities 
off  the  Atlantic  Coast.  Prompt  cooking  and  treatment  of  the 
fish  results  in  a  light-colored  oil  having  very  little  odor,  the  residue 
left  in  the  presses  being  of  great  value  as  a  fertilizer.  Although 
several  grades  of  oil  termed  crude,  brown,  light,  etc.,  are  produced, 


PAINT  OILS  AND  THINNERS 


13 


Transporting  Menhaden  from  net  to  deck  of  boat,  in  swinging  basket 

the  most  satisfactory  for  use  in  paint  is  that  grade  termed  "  light 
winter  pressed."  This  oil  is  of  a  pale  straw  color  and  has  a  high 
iodine  number  which  is  responsible  for  its  rapid  drying  value. 
It  contains  less  of  the  stearates  that  precipitate  from  crude  oil, 
but  sufficient  to  render  its  film  water-shedding  and  elastic.  The 
presence  of  too  great  a  quantity  of  stearates  is  apt  to  result  in  a 


A  big  catch  of  Menhaden  made  off  Xarragansett  Bay 


14 


PAINT  TECHNOLOGY  AND   TESTS 


very  soft  film,  and  the  use  of  hard  driers,  such  as  the  metallic 
tungates,  is  therefore  advisable  with  menhaden  oil.  When  mixed 
with  linseed  oil  paints  the  odor  of  menhaden  oil  is  sometimes 
noticeable,  but  it  disappears  entirely  after  such  paints  are  ap- 
plied. Its  use  with  linseed  oil  in  technical  paints  exposed  to 
the  salty  air  of  the  Coast  has  given  good  results,  often  pre- 
venting "  checking  "  and  "  chalking." 

The  following  constants  were  determined  on  samples  of  men- 
haden oil  received  in  the  writer's  laboratory: 


Sp.  Gr. 

Iodine 
Value 

Saponification 
Number 

Acid 
Number 

Light  

.927 

175.8 

187.9 

7  55 

Medium  
Dark  

.925 
.927 

178.7 
178.0 

187.6 
187.3 

6.19 

7  19 

Whale  Oil.  While  ordinary  whale  oil  is  too  dark  and  odorous 
to  ever  come  into  extensive  use  as  a  paint  oil,  it  is  probable  that 
the  refined  oil  will  be  utilized  in  the  manufacture  of  certain  techni- 
cal paints.  Whale  oil  is  boiled  from  chopped  whale  blubber,  the 
first  trying  being  the  lightest  in  color,  while  the  later  tryings,  as 
well  as  the  product  made  from  bones,  are  of  darker  color  and  of 
very  bad  odor.  Oil  of  mirbane  is  often  used  to  mask  this  odor. 
The  oil  contains  large  quantities  of  stearin  and  palmitin,  as  well 
as  wax-like  constituents  which  are  apt  to  be  thrown  out  of  solution 
in  very  cold  weather,  or  when  the  oil  is  mixed  with  other  oils. 
The  refined  oil,  when  ground  with  lead  and  zinc  pigments  and 
mixed  with  equal  parts  of  linseed  oil  and  treated  tung  oil,  dries 
to  an  elastic  and  soft  film.  Experiments  are  being  made  to 
utilize  whale  oil  in  the  linoleum  industry. 

The  analyses  of  samples  of  whale  oil  tested  by  the  writer  are 
as  follows: 


Sp.  Gr. 

Iodine 
Value 

Saponification 
Number 

Free  Fatty 
Acid 

Light  Refined 

924 

148 

1902 

1  2 

Dark  Yellow 

920 

142 

187 

70 

Dark  Brown    

.910 

140 

184 

18.0 

Sunflower  Oil.     Sunflower  oil  is  produced  largely  in  Russia 
and  Hungary,  finding  favor  in  those  countries  as  an  edible  oil. 


PAIXT  OILS  AND   THINNERS 


15 


The  ripe  seeds  of  the  sunflower  plant  contain  over  30%  of  oil 
which  is  very  pale  in 
color  and  of  a  pleas- 
ant smell.  It  has 
been  found  that  sun- 
flowers  may  be 
grown  to  advantage 
in  dry  parts  of  the 
United  States,  and 
if  suitable  yields  are 
obtained  from  a  few 
experimental  acres 
now  being  cultivated, 
the  industry  may  re- 
ceive encouragement 
in  this  country.  The 
oil  should  be  well 
suited  for  varnish 
making,  and  al- 
though  the  iodine  number  is  not  very  high,  it  dries  quite  rapidly. 

CONSTANTS  OF  SUNFLOWER  OIL 


Sp.  Gr. 

Iodine  No. 

Saponifica- 
tion  No. 

Acid 
No. 

.929 

128 

188 

4 

Cottonseed  Oil.  This  oil  is  expressed  from  the  seed  of  the 
cotton  plant,  varying  in  color  according  to  the  time  of  its  press- 
ing and  degree  of  refinement.  Being  edible  as  well  as  highly 
suited  for  soap  making,  very  little  of  it  comes  into  the  market 
as  a  paint  oil.  It  contains  large  quantities  of  stearin  and  has  a 
low  iodine  value,  making  it  a  slow  drying  oil.  Some  samples 
are  extremely  light  in  color  and  contain  less  mucilaginous  matter 
and  foots  than  is  present  in  ordinary  varieties. 
CONSTANTS  OF  COTTONSEED  OIL 


Sp.  Gr. 

Iodine  No. 

Saponifica- 
tion  No. 

Acid 
No. 

.922 

106 

190 

2.4 

16 


PAINT  TECHNOLOGY  AND  TESTS 


Corn  Oil.  As  a  by-product  in  the  manufacture  of  starch  and 
alcoholic  liquids,  this  material  comes  into  the  market  having  a 
golden  yellow  color,  and  an  odor  resembling  fermented  grain.  It 
has  a  lower  drying  value  than  cottonseed  oil,  and  its  use  in  the 
paint  industry  will  probably  be  limited  to  color  grinding,  where 
an  oil  with  a  semi-drying  value  is  often  desired.  Like  cottonseed 
oil,  it  belongs  more  properly  to  the  soap  oil  class.  It  contains 
glycerides  of  linoleic  and  especially  palmitic  acid. 

ANALYSIS  OF  CORN  OIL 


Sp.  Gr. 

Iodine  No. 

Saponification  No. 

Acid  No. 

.925 

118 

191 

9.5 

Rosin  Oil.  By  the  dry  distillation  of  rosin,  there  is  yielded  a 
series  of  heavy  dark  oils  consisting  principally  of  hydrocarbons, 
resinous  bodies,  and  free  acid.  These  oils  vary  in  their  saponifica- 
tion  number  from  10  to  60,  while  their  unsaponifiable  value  aver- 
ages about  80.  Of  the  grades  termed  first,  second,  third,  and 
fourth  run,  the  latter  two  are  superior  for  use  in  paints,  as  a  rule 
containing  less  free  acid  than  the  preliminary  runs.  Treatment 
with  steam  and  alkali  serve  to  neutralize  the  acid  nature  of  the 
oils  and  to  remove  impurities.  Refined  oils  are  lighter  in  color 
and  are  often  blown  and  bodied  to  fairly  rapid  drying  products, 
especially  when  treated  with  manganese  driers.  Rosin  oils  are 
seldom  used  with  lead  pigments,  on  account  of  the  presence  of 
sulphur  in  the  oils,  which  would  result  in  darkening.  Rosin  oil 
paints  work  very  smoothly,  even  when  they  are  curdled,  produ- 
cing glossy  surfaces.  The  rapid  checking  of  rosin  oil  paints  on 
wooden  surfaces  bars  the  use  of  this  oil  for  such  purposes. 

ANALYSES  OF  ROSIN  OILS 


Sp.  Gr. 

Iodine  Value 

Saponifica- 
tion  No. 

Acid  No. 

A  . 

B  

.966 
.99 

41 

48 

27 
38 

16.7 
10.0 

Hydrocarbon  Oils.     Several  grades  of  neutral  or  mineral  oils, 
varying  somewhat  in  gravity,  color,  and  quality,  are  produced 


PAINT  OILS  AND  THINNERS 


17 


as  the  last  distillate  in  the  refining  of  petroleum.  These  oils 
when  mixed  with  drying  oik  and  strong  driers  find  application 
in  the  manufacture  of  some  freight-car,  barn,  and  other  paints 
which  sell  at  a  low  price.  A  small  percentage  of  mineral  oil  is 
said  to  be  valuable  in  structural  steel  paints,  acting  as  a  preventa- 
tive  of  hard  drying  and  thus  keeping  the  film  soft  and  elastic. 
Streaking  and  sweating  is  apt  to  ensue  if  any  great  quantity  is 
used.  Mineral  oils  have  a  characteristic  bloom,  showing  a  greenish 
fluorescence  when  examined  by  transmitted  light.  This  bloom 
is  due  to  the  presence  of  some  strongly  fluorescent  material  which 


View  of  Stills  Where  Petroleum  Paint  Thinners 
are  Manufactured  (Waverly) 

is  shown  up  with  intensity  when  mineral  oils  are  exposed  to  ultra- 
violet rays  such  as  emanate  from  an  enclosed  arc  light.  Outer- 
bridge  1  first  proposed  this  test  for  mineral  oils,  and  he  has  worked 
out  a  "  fluorescent  scale,"  by  which  very  small  percentages  of 
hydrocarbon  oils  may  be  detected  in  other  oils.  Several  types  of 
so-called  debloomed  oil  have  been  placed  upon  the  market,  and 
although  such  oils  appear  under  ordinary  light  conditions  to  be 
free  from  bloom,  they  fluoresce  quite  strongly  when  given  the 
Outerbridge  test. 

1  Alexander  E.  Outerbridge,  Jr.:  "A  Novel  Method  of  Detecting  Mineral 
Oil  and  Resin  Oil  in  Other  Oils."  Proc.  14th  Annual  Meet.,  Amer.  Soc.  for 
Testing  Mater.,  Atlantic  City,  N.J.,  June  28,  1911. 


18 


PAINT   TECHNOLOGY  AND   TESTS 
ANALYSIS  OF  DEBLOOMED  MINERAL  PAINT  OiL1 


Sp.  Gr. 

Iodine  No. 

Saponification  No. 

Acid  No. 

.92 

12 

6 

0 

Pine  Oil.  This  oil  is  produced  by  the  redistillation  of  the 
heavy,  high  boiling  point  fractions  resulting  from  the  steam  distil- 
lation of  wood  turpentine.  It  is  a  heavy  straw-colored  oil,  and 
should  be  of  some  use  in  the  paint  and  varnish  industry,  where 
a  high  boiling  point  solvent  with  an  oxidizing  principle  is  desired. 
It  will  probably  find  application  in  the  manufacture  of  Baking 
Japans,  Asphalt  Paints  and  Enamels.  Its  oxidizing  and  solvent 
values  are  very  high.  It  has  a  distinctive  sweet  pine  smell, 
which  makes  it  popular  in  the  manufacture  of  turpentine  sub- 
stitutes from  petroleum  spirits. 

The  writer  has  examined  samples  of  this  material,  and  the 
following  appear  to  be  of  the  best  grade: 

CONSTANTS  OF  PINE  OILS 


No.  1 

No.  2 

Color 

Straw  Color 

Light  Yellow 

Specific  Gravity  at  15°  C.  .  . 
Boiling  Point  

.934 
192°  C. 

.936 
202°  C. 

Distillation  

Residue  on  Evaporation  .  .  . 
Polymerization  Test  

Flash  -Point 

95%     distils     between 
192-270°  C 
14.34% 
3f  %  unpolymerized  at 
end  of  \  hour 
72°  C. 

95%     distils    between 
202-280°  C. 
14.60% 
2^%  unpolymerized  at 
end  of  \  hour 
76°  C. 

Spot  Test 

Leaves  no  grease  spot 

Same  as  Pine  Oil  No.  1 

but  only  evaporates 
completely      in      24 
hours 

Turpentine.  By  direct  fire  or  steam  distillation  of  the  sap 
drippings  collected  in  pockets  cut  into  pine  trees,  there  is  obtained 
the  turpentine  of  commerce.  It  consists  largely  of  pinene  and 
isomeric  terpenes,  and  has  the  property  of  attracting  oxygen, 
with  the  formation  of  peroxides  which  stimulate  the  drying  of 
oils.  It  is  a  high-grade  solvent  for  various  gums,  and  is  therefore 

1  Oil  of  mirbane  present,  probably  as  a  deblooming  agent,  or  to  mask  the 
odor. 


PAINT  OILS  AND   THINNERS 


19 


used  in  the  manufacture  of  many  lacquers  as  well  as  for  thinning 
down  oil-gum  varnishes. 

REQUISITE  CONSTANTS  OF  PURE  GUM  TURPENTINE 

Color  Water  White 

Specific  Gravity  at  15°  C.  .  .862-.S75 

Boiling  Point About  156°  C. 

Distillation 95%  should  distil  between  153  and  165°  C. 

Residue  on  Evaporation    .  .  .Not  over  2% 

Polymerization    Not  over  5%  should  remain  unpolymerized  at 

end  of  half  hour 

Flash-Point    Over  40.5°  C. 

Spot  Test   No  grease  spot  should  remain  when  dropped  on 

paper  and  allowed  to  evaporate 
Water  .  ..None 


Wood  Turpentine.  High-grade  wood  turpentine  is  now  pro- 
duced by  the  steam  distillation  of  finely  cut  fat  pine  wood.  The 
lower-grade  qualities  are  often  produced  from  the  destructive 
distillation  of  sawdust,  stumpage,  etc.,  and  these  products,  on 
account  of  their  content  of  formaldehyde,  are  objectionable  in 
odor.  In  the  steam  distillation  process,  however,  a  high  quality 
product  is  obtained  by  cutting  out  the  heavy  fractions  and  re- 
distilling the  lower  and  purer  fractions.  It  has  a  high  oxidizing 
value,  causing  the  rapid  drying  of  paints  and  varnishes  to  which 
it  has  been  added.  Its  solvent  value  is  often  greater  than  that  of 
gum  turpentine.  When  properly  refined  it  has"  a  sweet  smell  and 
is  to  be  highly  recommended. 

Analyses  of  samples  of  pure  wood  turpentine  which  have  come 
to  the  writer  for  examination  follow: 


No.  1 

No.  2 

Sp.  Gr.  at  15°  C  
Boiling  Point  
Distillation:  95%  distils  be 
between 
Residue  on  Evaporation   .  .  . 
Polymerization  Test    

Spot  Test  

.862 
158°  C. 

158  and  185°  C. 
1.03% 
4.1  %  remains  unpoly- 
merized at   end  of  £ 
hour 
No  grease  spot  on  evap- 

.862 
162°  C. 

162  and  177°  .C. 
3.06% 
0.1    cc.  out  of    6  cc. 
unpolymerized  = 
1.66% 
No  grease  spot  on 

Odor 

oration 
Excellent 

evaporation 
Not  objectionable 

Color  . 

Water  White 

Water  White 

Flash  Point 

47.6°  C. 

20 


PAINT  TECHNOLOGY  AND  TESTS 


Petroleum  Spirits.  There  are  produced  from  Texas  crude  oil 
which  has  an  asphaltum  base,  and  Pennsylvania  crude  oil  which 
has  a  paraffin  base,  high  boiling-point  petroleum  spirits  which 
have  come  into  wide  use  as  paint  and  varnish  thinners.  When 
such  materials  have  the  proper  evaporating  value,  high  flash- 
point and  freedom  from  sulphur,  they  are  to  be  highly  recom- 
mended as  paint  ^thinners.  The  following  shows  the  analyses 
of  a  few  of  these  materials  examined  in  the  writer's  laboratory: 

PETROLEUM  SPIRITS 


Texas  Base 

California  Base 

Penna.  Base 

Color  

Water  White 

White 

Water  White 

Specific  Gravity  

.811 

.79 

.81 

Boiling  Point   

156°  C. 

138°  C. 

146°  C. 

Flash-Point    

44°  C. 

40.5°  C. 

43°  C. 

Residue  on  Evaporation    .  . 

.2 

.15 

.12 

Benzol.  "  Solvent  naphtha  "  or  160-degree  benzol  is  a  product 
obtained  from  the  distillation  of  coal  tar,  differing  from  benzine, 
a  product  obtained  from  the  distillation  of  petroleum.  It  is  a 
valuable  thinner  to  use  in  the  reduction  of  paints  for  the  priming 
of  resinous  lumber  and  refractory  woods  such  as  cypress  and 
yellow  pitch  pine.  The  penetrating  and  solvent  values  of  benzol 
are  high,  and  it  often  furnishes  a  unison  between  paint  and  wood, 
that  is  a  prime  foundation  to  subsequent  coatings,  preventing  the 
usual  scaling  and  sap  exudations  which  often  appear  on  a  painted 
surface.  Because  of  the  great  solvent  action  of  benzol,  it  should 
never  be  used  in  second  and  third  coatings.  The  writer  has 
successfully  painted  inferior  grades  of  cypress  with  a  paint  con- 
taining benzol  in  the  priming  coat. 

Benzine.  Benzine  is  seldom  used  in  paints  on  account  of  its 
rapid  evaporation,  which  is  apt  to  cause  pinholing  of  films  and 
other  surface  defects.  In  paints  of  the  dipping  type  where 
rapid  evaporation  is  essential,  benzine  finds  its  widest  application. 


CHAPTER  II 
A  STUDY  OF  DRIERS  AND  THEIR  EFFECT 

THE  proper  drying  of  oils  and  their  behavior  with  various 
siccatives  in  varying  quantity  is  an  interesting  problem,  and  ob- 
viously of  considerable  importance  from  a  practical  standpoint. 
Unfortunately  there  is  a  decided  scarcity  of  reliable  literature 
dealing  with  the  subject  for  the  guidance  of  those  concerned 
in  the  manufacture  or  application  of  siccative  products.  Further- 
more, when  the  problem  is  investigated,  it  is  not  difficult  to  see 
why  this  is  so. 

Uniform  Conditions.  At  a  glance  it  is  evident  that  a  decided 
obstacle  in  experimentation  on  the  drying  properties  of  oils  is 
the  difficulty  in  obtaining  identical  conditions  for  comparative 
purposes.  Inasmuch  as  a  multitude  of  factors,  such  as  uni- 
formity and  homogeneity  of  the  driers  and  the  oils  themselves, 
intensity  and  source  of  light,  temperature,  uniformity  of  applica- 
tion, and  many  others,  play  a  decisive  part  in  the  siccative 
tendencies  of  oils,  the  resources  and  ingenuity  of  the  chemist 
engaged  in  the  research  are  severely  taxed. 

Oxygen  Absorption.  It  is  a  well-known  fact  that  linseed  oil, 
when  applied  to  a  clean  surface,  such  as  a  glass  plate,  will  undergo 
oxidation  and  take  up  oxygen  to  the  extent  of  about  16%, 
forming  a  hard,  elastic,  non-sticky  product  which  has  been 
called  linoxyn.  This  material,  unlike  the  oil  from  which  it 
has  been  formed,  is  insoluble  in  most  solvents.  Other  oils, 
such  as  cottonseed,  hemp,  rape,  olive,  etc.,  are  more  fully  satisfied 
in  nature  and  have  not  the  power  to  absorb  the  amount  of  oxy- 
gen taken  up  by  linseed  oil. 

In  carrying  out  the  following  tests,  on  the  drying  of  oils,  a 
quantity  of  pure  linseed  oil  of  the  following  analysis  was  secured : 

Specific  gravity  at  15°  C.    ...  •. . . ... ."...-... 0.934 

Acid  number    5 

Saponification  number     191| 

Iodine  number    188 

21 


22  PAINT   TECHNOLOGY  AND   TESTS 

This  oil  was  distributed  into  a  number  of  8-oz.  oil  sample 
bottles,  and  to  a  series  of  these  bottles  was  added  varying  quan- 
tities of  a  very  concentrated  drier  made  by  boiling  oil  to  400 
degrees  Fahrenheit  in  an  open  kettle,  with  the  subsequent  addi- 
tion of  lead  oxide.  The  amount  of  drier  added  to  each  bottle 
varied  according  to  the  percentage  desired;  being  calculated 
on  the  lead  content  of  the  drier,  which  was  very  accurately 
determined  by  analysis. 

There  was  secured  in  this  manner  a  series  of  oils  containing 
varying  amounts  of  lead  oxide,  and  from  this  lot  was  selected 
a  certain  number  of  samples  which  would  be  representative 
and  typical  of  paint  vehicles  now  found  in  the  market. 

Another  series  of  tests  were  made  by  combining  with  a  large 
number  of  samples  of  pure  linseed  oil  as  used  above,  various 
percentages  of  a  manganese  drier  made  by  boiling  oil  at  400°  F. 
and  incorporating  therewith  manganese  dioxide. 

Still  another  series  of  tests  were  made  upon  a  number  of 
oils  into  which  were  incorporated  various  small  quantities  of 
lead  oxide  and  manganese  oxide  together,  using  the  standard 
driers  made  in  the  above  manner,  all  of  which  were  carefully 
analyzed  to  determine  their  contents. 

In  view  of  the  errors  in  manipulation  that  could  occur  where 
so  many  tests  were  made,  it  was  not  deemed  advisable,  in  carry- 
ing out  the  tests,  to  use  glass  plates  on  which  only  a  minute 
quantity  of  oil  could  be  maintained.  A  much  better  solution 
of  the  difficulty  presented  itself  in  using  a  series  of  small,  round, 
crimped-edge  tin  plates,  about  three  inches  in  diameter,  such 
as  are  used  for  lids  of  friction-top  cans. 

With  paints  it  is  impossible  to  secure  films  as  thin  as  those 
presented  by  layers  of  oil  on  glass,  nor  would  it  be  desirable 
to  secure  films  of  this  same  relative  thickness.  For  this  reason 
an  endeavor  was  made  to  conduct  the  following  tests  with  films 
of  the  same  relative  thickness  as  that  possessed  by  the  average 
coating  of  paint.  The  drying  of  the  films  did  not  take  place 
in  the  same  short  period,  nor  in  the  same  ratio,  as  with  the  thin 
layer  that  is  secured  by  flowing  oil  upon  glass.  The  results, 
however,  are  more  practical,  and  of  greater  value  to  the  manu- 
facturer. 

The  cans  were  carefully  numbered  in  consecutive  order, 
corresponding  to  the  numbers  on  the  various  samples  of  oil. 


STUDY  OF  DRIERS  AND   THEIR  EFFECT  23 

A  very  small  quantity  of  oil  was  placed  in  each  of  the  can  covers, 
which  were  previously  weighed,  and  allowed  to  distribute  itself 
over  the  bottom  surface  thereof.  Reweighing  of  the  covers 
gave  the  amount  of  oil  which  was  taken  for  each  test.  The 
test  samples  in  the  covers  were  all  placed  in  a  large  box  with 
glass  sides,  having  a  series  of  perforated  shelves.  In  the  side  of 
this  box  is  an  opening  through  which  a  tube  was  passed,  carry- 
ing a  continual  current  of  air  washed  and  dried  in  sulphuric  acid. 
Oxidation  of  the  oil  films  commenced  at  once,  and  the  amount 
of  oxygen  absorbed  was  determined  at  suitable  periods  by 
weighing,  the  increase  in  weight  giving  this  factor.  This  test 
was  kept  up  for  a  period  of  twenty  days. 

A  test  was  also  made  in  the  same  manner  with  a  current  of 
damp  air  passing  into  the  box,  to  observe  the  relative  oxida- 
tion under  such  conditions.  A  chart  of  the  results  obtained 
has  been  made  (Table  VI),  to  show  the  effect  of  the  various 
driers. 

Results  of  Tests.  The  following  outline  will  present  to  the 
mind  of  the  reader  the  most  salient  points  which  have  been 
gleaned  from  these  experiments,  and  which  should  give  the 
manufacturer  definite  knowledge  as  to  the  best  percentage  of 
oxides  to  use  either  in  boiled  oil,  paints  or  varnishes. 

In  the  case  of  lead  oxide,  an  increase  in  the  percentage  of 
lead  oxide  in  the  oil  causes  a  relative  increase  in  the  oxygen 
absorption,  but  when  a  very  large  percentage  of  lead  has  been 
added,  the  film  of  oil  dries  to  a  leathery  skin. 

In  the  case  of  manganese  oxide,  the  increase  in  oxygen  ab- 
sorption on  the  first  day  is  much  more  pronounced  than  is  the 
case  with  lead  oxides.  Furthermore,  the  oxidation  of  man- 
ganese oils  seems  to  be  relative  to  the  increase  in  manganese 
up  to  a  certain  period,  when  the  reverse  of  this  law  seems  to 
take  place,  and  beyond  a  certain  definite  percentage  of  man- 
ganese, added  percentages  seem  to  be  of  no  value.  It  was 
furthermore  observed  that  the  films  dry  to  a  more  brittle  and 
harder  skin  than  is  the  case  when  lead  oxide  is  used.  The  oxygen 
absorption  with  oils  high  in  manganese  has  been  noticed  to  be 
excessive,  and  the  film  of  oil  becomes  surface-coated,  drying 
beneath  in  a  very  slow  manner;  a  condition  that  often  leads 
to  checking.  The  critical  percentage  where  the  amount  of 
manganese  appears  to  give  the  greatest  efficiency  seems  to 


24 


PAINT   TECHNOLOGY  AND    TESTS 


8 

CO  00 

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STUDY  OF  DRIERS  AND    THEIR  EFFECT 


25 


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26  PAINT   TECHNOLOGY  AND   TESTS 

be  0.02%.  This  critical  percentage,  as  it  may  be  termed, 
should  not  be  exceeded,  and  any  added  amount  of  man- 
ganese has  the  effect  of  making  the  film  much  more  brittle 
and  causes  the  so-called  " burning  up"  of  the  paint.  The 
loading  of  paint  with  drier  and  the  bad  result  therefrom  may  be 
explained  to  some  extent  from  the  above  results. 

In  the  same  way  with  lead  driers,  excessive  amounts  of  lead 
oxide  seem  to  have  no  beneficial  effects  on  the  drying  of  an 
oil,  and  when  the  percentage  which  seems  to  be  the  most  bene- 
ficial, namely  0.5%  lead  oxide,  is  exceeded,  the  film  is  apt  to 
become  brittle. 

Oils  containing  lead  oxide  driers  are  less  influenced  in  their 
drying  tendencies  by  conditions  of  moisture  in  the  atmosphere 
than  oils  containing  manganese,  but  frequently,  however,  the 
former  dry  much  better  in  a  dry  atmosphere.  As  a  general 
rule,  varnishes  rich  in  manganese  dry  more  quickly  in  a  dry 
atmosphere,  while  those  containing  small  quantities  dry  more 
quickly  in  a  damp  atmosphere. 

Volatile  Products  Formed.  It  was  furthermore  noticed  in 
these  tests  that  sulphuric  acid,  placed  in  dishes  on  the  bottom  of 
the  large  box  in  which  the  samples  of  oil  were  drying,  as  dis- 
colored and  turned  brown  after  several  days,  showing  that  the 
acid  had  taken  up  some  material  of  a  volatile  nature  that  was  a 
product  of  the  oxidation. 

Another  curious  feature  of  these  tests  was  the  development 
of  a  peculiar  aromatic  odor  which  was  given  off  by  the  oils 
upon  drying  in  dry  air.  When  the  oils  were  dried  in  moist  air, 
a  rank  odor  resembling  propionic  acid  was  observed,  and  this 
led  the  observer  to  believe  that  a  reaction  was  effected  by  the 
absorbed  oxygen,  that  caused  the  glycerin  combined  with  the 
linoleic  acid  as  linolein  to  split  up  into  evil-smelling  compounds. 
It  has  been  suggested  that  the  oxygen  first  attacks  the  glycerin, 
transforming  it  into  carbonic  acid,  water,  and  other  volatile 
compounds,  which  are  eliminated  before  the  oil  is  dried  to 
linoxyn.  Toch,1  however,  has  shown  that  the  drying  of  linseed 
oil  gives  off  only  very  small  percentages  of  carbon  dioxide. 
Mulder  has  observed  that  in  the  process  of  linseed  oil  being 
oxidized,  glycerin  is  set  free,  which  becomes  oxidized  to  formic, 

irToch:  The  Chem.  and  Tech.  of  Mixed  Paints,  p.  89.     D.  Van  Vostand 
Co.,  N.  Y. 


STUDY  OF  DRIERS  AND   THEIR  EFFECT  27 

acetic,  and  other  acids,  while  the  acid  radicals  are  converted  by 
oxygen  into  the  anhydrides,  from  which  they  pass  by  further 
oxidation  into  linoxyn. 

Auto-Oxidation  of  Oil.  The  theory  of  auto-oxidation  of 
linseed  oil  has  been  very  ably  treated  by  Blackler,  whose  experi- 
ments indicated  that  during  the  drying  process  the  slow  absorp- 
tion of  oxygen  was,  at  a  critical  period,  followed  by  a  rapid 
absorption,  which  he  attributes  to  the  presence  of  peroxides. 
The  materials  produced  by  this  peroxide  formation  may  act 
as  catalyzers  and  accelerate  the  formation  of  more  peroxide. 
Lead  and  manganese  oxides  may  also  be  oxidized  to  peroxides 
by  the  action  of  oxygen,  and  in  this  event  might  act  as  very 
active  catalyzing  agents  or  carriers  of  oxygen.  Bladder's 
statement,  that  the  presence  of  driers  do'  not  increase,  but 
h&ve  a  tendency  to  decrease  the  initial  velocity  of  oxygen 
absorption,  has  been  confirmed  by  these  experiments,  but  it 
has  been  noticed  throughout  the  tests  that  the  driers  have  an 
accelerative  action  at  a  later  period. 

Effect  of  Metals  on  Drying  of  Oils.  Some  most  interesting 
results  were  secured  by  dipping  extremely  fine  copper  gauze 
into  linseed  oil,  and  then  suspending  the  gauze  in  the  air.  The 
adhesion  of  the  oil  to  the  copper  caused  the  formation  of  films 
between  the  network,  and  remarkable  drying  action  was  observed. 
The  copper  or  any  superficial  coating  of  copper  oxide  which 
may  have  been  present  on  the  metal,  undoubtedly  affected  the 
result  to  some  extent.  It  has  been  found  that  metallic  lead  is 
even  more  efficient  than  copper  in  this  respect,  but  this  may  be 
due  to  the  action  of  free  acid  in  the  linseed  oil,  forming  lead 
linoleates,  products  that  greatly  accelerate  drying.  Another 
interesting  experiment  was  made  by  immersing  pieces  of 
gauze  cloth  in  linseed  oil.  After  the  excess  oil  had  been 
removed,  by  pressing,  the  cloth  was  again  weighed  to  deter- 
mine the  amount  of  oil  used  for  the  experiment.  The  increase 
in  oxygen  absorption  in  this  case  was  very  rapid,  and  the  result 
obtained  confirmed  the  results  in  the  other  experiments. 

In  order  to  secure  a  more  evenly  distributed  state  of  the  oil, 
tests  were  conducted  by  saturating  pieces  of  stiff  blotting  papers, 
and,  after  exposure,  weighing  as  usual. 

Influence  of  Light.  The  influence  of  light  on  the  drying  of 
oils  is  unquestionably  a  potent  one.  The  practical  painter  knows 


28  PAINT  TECHNOLOGY  AND   TESTS 

that  a  certain  varnish  will  dry  quicker  when  exposed  to  the  light 
than  when  in  the  dark. 

Chevreul  was  one  of  the  first  pioneers  in  this  field  of  research 
to  observe  the  effects  of  colored  lights  on  drying,  and  he  claimed 
that  oil  exposed  under  white  glass  dried  more  rapidly  than 
when  exposed  under  red  glass,  which  eliminates  all  light  of  short 
wave  lengths. 

Genthe  obtained  interesting  results  in  the  drying  of  oil  sub- 
mitted to  the  effect  of  the  mercury  lamp.  Oxidation  without 
driers  was  effected  probably  through  the  formation  of  peroxides. 
In  commenting  on  this  subject,  Blackler  l  gives  a  description  of 
the  use  of  the  Uveol  Lamp,  which  is  similar  to  the  mercury 
lamp,  but  has,  instead  of  a  glass  casing  which  cuts  off  the  valuable 
rays,  a  fused-quartz  casing  which  allows  their  passage. 

Driers  in  Boiled  Oil.  In  the  boiling  of  linseed  oil,  by  certain 
processes  the  oil  is  heated  to  250°  F.  and  manganese  resinate 
is  incorporated  therein.  It  goes  into  solution  quite  rapidly. 
In  other  processes  the  oil  is  heated  to  400°  F.  or  over,  and 
manganese  as  an  oxide  is  boiled  into  the  oil.  Although  it  is 
unsafe  to  say  that  a  small  percentage  of  rosin,  such  as  would  be 
introduced  by  the  use  of  resinate  driers,  is  not  harmful,  yet  it 
appears  that  this  process  should  give  a  good  oil,  inasmuch  as  it 
has  been  found  that  no  matter  whether  the  manganese  is  added 
to  the  oil,  as  a  resinate,  borate  or  oxide,  practically  the  same 
drying  effect  is  noticed  in  every  case  where  the  percentage  of 
manganese  is  the  same.  It  is  the  opinion  of  some,  however, 
that  the  resinate  driers  are  not  as  well  suited  for  durability  as 
oxide  driers.  However,  if  a  boiled  oil  is  found  to  contain  on 
analysis  a  small  percentage  of  rosin  less  than  0.5%  or  a 
percentage  only  sufficient  to  combine  with  the  metal  present, 
it  should  not  be  suspected  of  adulteration.  Practical  tests 
should  be  made  with  such  oil  along  with  an  oil  made  with 
an  oxide  drier,  before  pronouncing  on  their  relative  values. 
Inasmuch  as  the  addition  of  certain  driers  to  linseed  oil  lessens 
the  durability  of  the  film,  it  is  more  practical  to  use  the  smallest 
amount  of  drier  that  will  serve  the  purpose  desired,  that  is, 
set  the  oil  up  to  a  hard  condition  which  will  not  take  dust  and 
which  will  stand  abrasion. 

'M.  B.  Blackler:  "The  Use  and  Abuse  of  Driers,"  P.  and  V.  Society, 
London,  Sept.  9,  1909. 


STUDY  OF  DRIERS  AND  THEIR  EFFECT  29 

The  results  of  this  investigation  would  indicate  that  when  lead 
or  manganese  linoleates  are  used,  the  most  efficient  drying  is 
shown  with  0.5%  lead  or  with  0.02%  manganese,  or  with  a  com- 
bination of  0.5%  lead  and  0.02%  manganese. 

Until  more  definite  results  have  been  obtained  with  the 
tungates,  which  will  probably  prove  of  exceptional  interest  as 
driers,  the  above  driers  will  probably  be  used  to  the  greatest 
extent. 

Co-operative  Drying  Tests.  A  series  of  important  drying  tests 
made  by  members  of  a  special  committee  l  appointed  by  the 
American  Society  for  Testing  Materials,  of  which  the  writer 
was  chairman,  is  herewith  shown: 

"  At  the  January  meeting  of  Committee  D-l,  a  sub-committee 
consisting  of  the  following  members  was  appointed  to  investigate 

paint  vehicles: 

G.  B.  Heckel, 

Glenn  H.  Pickard, 

Allen  Rogers, 

A.  H.  Sabin, 

H.  A.  Gardner,  Chairman. 

"  At  a  subsequent  meeting  of  the  sub-committee  it  was  deter- 
mined to  start  the  investigations  with  a  series  of  tests  on  certain 
drying,  semi-drying,  and  non-drying  oils,  determining  their 
drying  values,  rate  of  oxygen  absorption,  etc.,  when  spread  out 
in  thin  films.  A  quantity  of  the  following  oils  was  selected  for 
the  tests  and  subsequently  secured  from  sources  known  to  be 
reliable : 

Lead  and  manganese  linoleate  drier.2        Cottonseed  oil. 
Lithographic  linseed  oil.  Sunflower  oil. 

Boiled  linseed  oil  (resinate  type).  Menhaden  oil. 

Boiled  linseed  oil  (linoleate  type).  Chinese  wood  oil,  raw. 

Blown  linseed  oil  (containing  drier        Chinese  wood  oil,  treated. 

while  being  blown).  Perilla  oil.3 

Heavy  mineral  oil.  Lumbang  oil.3 

Rosin  oil.  Dry  rosin  20%,  boiled  in  80%  lin- 

Soya  bean  oil.  seed  oil. 

Corn  oil. 

1  Sub-Committee  C  of  Committee  D-l,  on  Testing  Paint  Vehicles.     Proc. 
Amer.  Soc.  for  Test.  Mater.,  1911. 

2  The  drier  used,  upon  analysis,  showed  the  presence   of  4.36%   PbO 
and  2.51%  MnO2. 

3  The  lumbang  and  perilla  oils  were  imported  and  arrived  subsequent 
to  the  starting  of  the  tests.     They  were  therefore  not  included  in  the  tests. 


30  PAINT   TECHNOLOGY  AND   TESTS 

11  Four-ounce  sample  bottles  of  each  oil  were  sent  to  the  Com- 
mittee members,  with  the  request  to  proceed  with  the  tests 
along  the  lines  agreed  upon  at  the  Committee  meeting.  The 
instructions  for  making  these  tests  are  outlined  as  follows: 

(a)  A  series  of  small  glass  plates,  approximately  5  by  7  ins., 
are  to  be  prepared  by  each  member  of  the  Committee.  These 
plates  are  to  be  thoroughly  cleaned  and  carefully  numbered  and 
weighed  upon  a  chemical  balance.  The  oils  to  be  used  for  the 
tests  are  to  be  numbered  corresponding  to  the  plates.  A  test 
of  each  oil  is  to  be  made  by  painting  it  upon  the  surface  of  a 
glass  plate  with  a  camers-hair  brush,  subsequently  weighing  the 
plate  and  the  oil.  These  tests  are  to  be  exposed  under  constant 
conditions  of  temperature,  if  possible,  for  three  weeks'  time, 
making  weighings  of  each  plate  every  day  for  six  days  and  then 
every  other  day  for  twelve  days. 

(6)  Another  series  of  tests  shall  be  made,  in  which  80% 
of  raw  linseed  oil  is  to  be  combined  with  each  of  the  above 
oils  named.  Previous  to  making  any  of  the  tests,  there  should 
be  added  to  each  oil,  or  to  each  combination,  5%  of  a  drier 
containing  lead  and  manganese.  The  drier  to  be  used  is  of  the 
standard  grade  submitted,  together  with  the  oil  samples.  The 
results  of  the  tests  are  to  be  charted  and  submitted  at  the  end 
of  the  tests,  so  that  they  may  be  compared  with  the  results 
obtained  by  each  member  of  the  Committee. 

(c)  If  possible,  the  oils  and  mixture  of  oils  used  in  the  above 
tests  are  to  be  ground  with  pure  silica  and  painted  out  upon  sized 
paper,  three-coat  work,  the  films  to  be  stripped  and  tested  for 
strength  upon  a  paint  filmometer,  at  two  periods  two  months 
apart." 

The  drying  of  oils  to  a  firm  surface  when  spread  in  a  thin  layer 
is  accompanied  by  an  increase  in  weight,  due  to  the  absorption 
of  oxygen.  The  percentage  of  oxygen  absorbed  often  affords  a 
criterion  of  the  drying  of  the  oil  under  examination,  and  this 
factor,  together  with  data  regarding  the  appearance  of  the  oil 
film,  should  be  taken  into  consideration  when  judging  the  value 
of  an  oil  or  oil  mixture.  Conditions  of  light,  air,  temperature, 
etc.,  often  cause  great  variations  in  the  drying  of  oils  and  the 
percentage  of  oxygen  absorbed,  as  shown  by  the  results  obtained 
in  the  following  tests.  Although  it  was  impossible  in  these  tests 
to  have  the  conditions  under  which  each  experimenter  worked 


STUDY  OF  DRIERS  AND   THEIR  EFFECT  31 

parallel  in  nature,  the  tests  afford  nevertheless  considerable 
information  for  guiding  future  work  of  a  similar  nature. 

An  examination  of  the  results  obtained  showed  generally  that 
the  greatest  increase  in  weight  occurred  during  the  period  in 
which  the  oil  dried  up  to  a  firm  film.  This  occurred  in  most  cases 
within  48  hours.  After  this  period  a  slight  increase  in  weight 
was  often  noticed,  and  then  a  more  or  less  steady  decline,  varying 
with  the  oil  examined.  Had  the  oil  tests  been  continued  for  a 
greater  length  of  time,  a  much  greater  loss  might  have  been 
observed. 

It  was  impossible  to  include  in  the  tests  the  oil-silica  film  work, 
on  account  of  lack  of  time.  It  is  believed,  however,  that  these 
tests  should  be  conducted,  as  they  would  throw  much  light  on 
the  elasticity  and  strength  given  to  paint  films  by  various  oils. 


32 


PAINT   TECHNOLOGY  AND   TESTS 


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Gardner 
Sabin  . 

t>:«i  1 

il 

Gardner 

Sabin  . 
Pickard  . 

Rogers  1 
North,  } 

STUDY  OF  DRIERS  AND   THEIR  EFFECT 


33 


Remarks. 

•a£°!a 

**SK 

1^3° 

si:ti 

*.s  >  § 

•2§« 

irfi 

lb-& 

«:if 

-H     1>    30 

2 

1      g1       ' 

00 

»      i 

X 

S      1 

fc 

1         t^ 

1 

CD 

t         1 

1       8 

CN 

2 

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a 

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06         r^ 

8 

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S     S. 

!    § 

CN 

x"         co«o         °. 

- 

t*  o             r* 

05             XO            g 
0             OCO             °. 

Wt.  of  Oil 
for  Test, 

tfr.'iins. 

r*             COIN             X 

^                 CO'H                 r-l 

O             t^X             CO 
^*            XX            t^* 

6  -      66        CN 

1 

o            -:-0         „,    . 

i  ii  11 

C3           r^a.         DiZ 

a   a 
O  U 


O  . 

i  : 

OD 

Z  J 

^  O 

O  Q 


Dried  to  firm 
m  in  2  days. 


il 


II 


kC  CO 
X    CMOS 


O   t^CO 


CN    COOS 

05 


C5    OO 


Gardner 
Sabin  .  .  . 
Pickard  . 


| 
| 

5 
2 

s 

£ 

T 

ls.o  c—  1,        ~J*.~o 

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34 


TECHNOLOGY  AND   TESTS 


Remarks. 

Oil  lost  in  weight 
throughout  test  on 
account  of  presence  of 
volatiles.  No  drying 
action  observed.  Film 
wet  at  end  of  test. 

(  Broken  before  weigh- 
)  ings  were  made. 

(  Remained  oily  dur- 
\  ing  entire  test. 

05 

1             1 

1 

00 

— 

1 

- 

I             I 

CD 

-S       1  1 

S 

~   00 

10 

1      1  1 

3 

rt     • 

-| 

1 

2 

1      1 

l 

.9 

2 

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rt  co 

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fl 

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CO 

9 

i 

. 

1      1 

1 

. 

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-i 

a 

- 

1      1 

1 

CO 

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(M 

-i   "^ 

10 

-S       l 

"i 

« 

-2       1 

""   10 

CO 

-5       1  l 

CO 
(N 

* 

~3       1 

"  S 

- 

-S       1  i 

CN 

rt  GO 

Wt.  of  Oil 

for  Test, 
grams. 

1       I  1 

d 

1 

d 

Observer. 

1     11 

al 

00 

tf^: 

J 

.  o 

n 

-    Z 

S3 
I  ^ 
^^ 


j|l    || 

1  Lost  in  weight  throughout  test. 
2  Gained  in  weight  throughout  test. 

rh 

1     -3 

CO 

00                     1         00 

i^            ~  d 

1          1     1 

2       1    1 

1-5"  d 

5       1    l-S 

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GO                  CO         l         O5 

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CO                  GO'"  GO'*1   »0 

•*                  "?„   ^M   C0- 

d            odd 

w               :     73    " 

i  Mil 

OQ      PH     PH  ^ 

STUDY  OF  DRIERS  AND   THEIR  EFFECT 


35 


Remarks. 

[  Film  tacky  until  3d 
\  day.  Clear  and  fairly 
{  firm  after  4th  day. 

Sticky,  end  of  1st 
day;  tacky,  end  of  2d 
day;  slightly  tacky, 
end  of  10th  and  38th 
days. 

O5 

1        |l 

1 

2 

co   .a? 

CN         1  •* 

1 

£ 

!    3l 

1 

~ 

CO 

3     1  1 

5 

IO 

2 

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1 

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§ 

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=       — 

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- 

.     . 

1 

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CO 

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1 

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CM 

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- 

10       t-CO 

t^.     dos 

CN 

00 

Wt.  of  Oil 
for  Test, 
grams. 

d     do 

6 

Observer. 

|  || 

o   Is 

0  O 

ii 

o  o 

II 


ffl  j 

II 


(  Clear,  firm  film  ob- 
(  served  at  end  of  2d  day. 

Tacky  at  end  of  1st 
and  2d  days.  Dry, 
end  10th  day. 

IO   i         i 
06  1       1 

CO      1   CO          1 

co    1  d      1 

,8 

1     00 

1 

s  ' 

I 

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§ 

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00 

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§ 

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=  SS  3 

003 
iO   t»"- 

"+      t>- 

2fcS   3 

CN    0010       CSI 
CN    INI"       CM 

d  do     6 

4)      -*2      nj     • 

Remarks. 

Tacky  throughout  test. 

Too  much  on.  Show- 
ed constantly  increas- 
ing loss  owing  to  the 
fact  that  it  did  not  dry 
and  ran  off  glass. 
Oily  on  1st  and  2d 
days.  Tacky,  end  of 
10  and  38  days. 

i 

a 

i 

a 

I 

£ 
§ 

05 

1 

i    i     i 

2 

00 

i    i     i 

S 

1 

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CO 

00 

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0 

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1 

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1 

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00 

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1 

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CO 

51     I     d 

IO 

o 

10 

i    i     S 

-# 

0 
CO 

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CO 

00 

i    i     s 

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CN 

lO 

1               1                  ^ 
CN 

,-H 

•*»< 

"?  1        1         °1 

•41               1                  (N 

|i 

CN 

d 

i    i    i 

6 

Observer. 

Gardner 

•'-    •    Jfi                   B      • 

a         «          §35 

S          "o             |  S 

36 


TECHNOLOGY  AND   TESTS 


Is 

S; 
I 
B 


Remarks. 

f  Film  dried  up  nicely 
|  during  3d  day,  but  re- 
(  mained  slightly  soft. 

f  Oily  at  end  of  1st  and 
<!  2ddays.  Slightly 
[  tacky,  end  of  10th  day. 

1 
P 
_g 

43 
bO 

1 
_g 

^fl 

i 
1 

O5 

co 

CO 

00 

06 

8 

00 

£ 

oc 

CO 

CO 

C5 

t>l 

1 

10 

CO  CM 

,-110 

-too 

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05 

05 

CO 

06 

CM 

00 

0       CO 

00          TJH 

S? 

05 

- 

1    1 

iO 

2  1 

0 

q     £ 

00           T}< 

1   1 

OS 

1   35    1 

00 

o    3 

00            TJH 

05 
0 

- 

CM 

. 

00 

1  1 

. 

•*       COCO       CM 

00          CM-H          T* 

»OO       O 

„ 

S  8S  s 

*o  o     o 

CO 

iC       iO  CO       O 
00       9-1        » 
COrH       0 

. 

00       0»0       CM 
^       •*•*       O 

COrH         CM 

- 

T*          -t  rH          OO 

2  *«  * 

CO       IO  CD       CO 

d     do     d 

1 
o 

i-,       •       <—  —  ^ 

{Film  soft  and  sticky 
throughout  test.  Very 
soapy  in  appearance. 

c> 

C£ 
P 

I      1 

°5 

CO 

2     1 

u 

i     ; 

1      I 

9 

S 

•j 
t- 

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1 

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t^          if 

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J                  iO 

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2     3~l   3 

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3     «      1 

5       CO          1 

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t^               CO           1          CO 

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1                    10          1-H             1 

2 

co 
1       °^ 

1         CD 

t>-        Ifi        OS 
IO                  rH          CO          CO 
t>                  t>^          rH          CO 

CO       »0       05 
00             •*       CO       O5 

•*                  |>'  N    rH          CO 

05           t^           Tf< 
CO                t^;         CM         rH 

•«t         oo     i>     t^ 

3     5  1  § 

CM       CM       CO 

OS       ^  CM       CM       CO 

>o         « 
o        ^ 
d        o 

d     d 

Gardner  . 
Sabin  .  . 

li 

PJ  pi  Z 

00 


(  Film  tacky  at  end  of 
(  test. 

(Tacky,  end  of  1st  and 
2d  days.  Dry,  end 
10th  day. 

1     1 

1 

2  iS     ' 

1  S 

I 

d  1 

1 

1  SS    1 

1  1 

00 
CM 

00 

1    IS? 

X 

coo 

d  05 

1 

•«t 

1  ^ 
1  t> 

CO    CO 
0   05 

CO 
00 

OO  O5 

1  «N    1 

1     O  00         I 

oo         r-i 

iO    05    i         CD 

d  d  1      05 

CM  CO 
CM  CM          1 

rHOS             1 

1  ' 

CM 

S 

*.$z  s 

CO  rH          CO 
CM     rH  t>-         CO 

O     rH  rH          QO 

CO       00 

«?  1  1    h 

00      1   CM       OS 

rH  CN 

06  CM'CN 

1         OS 

)         CO 

SSS  2 

d  do     d 

III 

II 

STUDY  OF  DRIERS  AND   THEIR  EFFECT 


37 


Remarks. 

Film  showed  very 
little  hardening  and 
remained  soft  and 
tacky. 

ft 

111 
||1 

OS 

1 

l  l    l 

00 

o 

00 

r  i 

1  (N         1 

tw 

1 

1     1          1 

2 

os 

2113 

>o 

1 

Icl       1 

3 

0 
00 

OS 

1  1    n- 

\     \         CO 

I  9 

1 

IS   1 

-S     2 
3 

0 

00 

1  1  2 

M   ' 

CM 

1             12         1 

•=           C 

i 

os 

81    « 

<*    1         <N 

I  • 

1 

»C  X 
OS  O        1 

1  - 

00 

9|       « 

1  -; 

1 

3S  i 

o 

£ 

1  1  5 

, 

o 

00 

O  t*-       CO 

, 

3    IS  1 

CO 

oq 

OOCM       to 
«50       00 

- 

oq 

000       ~ 
•     •       ^j 

1-1 

to 

-s.t~      -' 

Wt.  of  Oil 
for  Test, 
grams. 

0 
CM 

d 

t^to     eo 

Tf  CO       00 
CM  ^H       1C 

do     d 

1 

"        ~  ~    "^ 

II 


55 


sr-i  in 


I  SI  I 


2     II 


5SS     i 

WO5         I 


I    ll  I 


2    SI 


too 

I  WO         I 

OS  00 


CM  O 

OS          •*    i        O 

~i       os"  I      d 


os       oqoq     <N 

^  C505        OS 


do     cs 


o      oo     o 


ii  y 


II  ll 

o     MPH  tf^; 


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<NO 

I  5S     I 


to      I     I  O 


5  SS    S 


COCM          CO 


tO     OSTf          CM 

r-i      t>It<I  O 


06  dr^       co 


CO     000          CO 

d   ost^       06 


d  d 


Roger 
North 


38 


PAINT   TECHNOLOGY  AND   TESTS 


II 


l 


Remarks. 

Good  firm,  glossy 
film  shown  at  end  of 
1  2d  day. 

1 

to 

gj 

05 

1      « 

1      c 

CO 

O5 
O 

1  1 

!5 

co 

§1 

cc 

0 

d 

IQ 

CO  <N 

co  oo 

2 

d 

1  °- 

1         CO 

1    s 

1 

d 

.9      IN 

00       CN 

d     c 

I   S 

bC 

1     3 

1       I 

i  i 

•3      o 

oo     v. 
o     c 

i  ! 

fl 

1   dS    1 

|      « 

"fl 

CO 
00       O 

d     c 

I   S 

1            " 

d  06 

0 

03 
0 

O 

d 

10 

O5  1C       lO 

rH         rnd         S 

„ 

CO         SS         3 

co 

rH          g 

X        01 

Tf             05 

- 

q     So     co 

rH 

.o  ss  s 

d          Tf  d          rH 

|f 

O         OO        rH 
rH          lOTf          <N 

o     do     d 

1 

S 

1  1 

o   S 

1  ll 

.2    oo 

CH  tfz; 

Remarks. 

.3 

O  bcS 

.a* 

Sticky,  end  1st 
day.  Slightly  sticky, 
end  2d  and  10th  days. 

05 

8 

d 

oo 

O          i   (M 

d       1  d 

- 

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0 

d       1 

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1C  1C 

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05 

0? 

Q      S 

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05        i-I 

<N 

d 

s 

fl 

1  IS  1 

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s 

CO       O 

d          rH 

0 

oo 

00 

H-  1               O5 

1000 

1      ^       \ 

1               °° 

o 

CO       (N 

O          rH 

1      d 

£     ,. 

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1         <N  <N          I 

005          1 

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d 

1      d 

. 

cot--     •* 

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„ 

rH         Tt<  OS         O5 
O         rHO         03 

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0  1C       <N 
O5        t>  00        t>. 

00          rHO          05 

C, 

t^oo     o 

06     do     o 

- 

t^        Tt*  b-        (N 

t^         dO         rH 

It 

Tt^       O^l  1C       O 

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05         (NO        rH 

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d     do     d 

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1 

1       '^^1 

1  11  II 

ii 

3  w 
00 

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finPn 

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12  H 

SS 

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ll 


i! 

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1      00 

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1    S 

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10           rH,-H       05 

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TjH           1C  O      1C 

d     do   d 

ill 

STUDY  OF  DRIERS  AND   THEIR  EFFECT 


39 


i  s  .5  is          os-5-o 

(  Clear  and  firm  film 
(  shown  after  3d  day. 

Dry  at  end  of  1st  day. 

1           31          1 

1  SI  1 

3     IS    I 

-   ,S  | 
2 

1     SI     1 

1  SI  1 

g 

3      111 

dill 

H 
O 

1     S5    1 

H 

1  sn  1 

H 
§ 

CO 

3      MS 

^    i: 
0  0 
a   s 

CO 

§  II  5 

1      15     1 

00 

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H 

d                Hi 

3    ft    1 

! 

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5 

1  15  1 

c^          ^   |         ^ 

2       2        °° 

o 

fe  o 

«3,  8 

CN    00    1     00 

O 
O 
O 

^JCO              I 

oos        1 

H     O 

«   a 
H   a 

1    Hod    1 

1 

Tf                         OS 

«1      »>  1      « 

S      2        °° 

^    CO         0 
(N     00    1      OS 

g 

B 

1         do        1 

II 

CO.H 

ICO  o     i 
060     1 

2 
1 

«       1  |      S 

-J<          1    1        t^ 

S 

o 
°°.    1    1    m, 

04      1     1     OS 

1 

^         ^06       d 

^    ^°°    S 

oo   t>;  t^-   q 

oi   OS^H   cs 

s 

COO          O 
rt<             1C  O          O 

TJ         ^jr^       d 

X  i-i    O 
00     Or*     CO 

oi   doi   os 

<>*«       o 

q         q  *H       I-H 

q    £^    S 

N   I-H  co   d 

^          lei      ei 

SSss 

,S      S 
^         loo 

q   rfco   q 

CO             >O  CO          O 

d        dd      d 

0    §0    S 

d  do  d 

1         :"H    7^ 

1    ||  || 

liffi 

a  -g.t;  s  o 

Remarks. 

Loss  observed  due 
to  presence  of  vola- 
tilcs.  Firm,  clear  film 
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PAINT   TECHNOLOGY  AND   TESTS 


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STUDY  OF  DRIERS  AND   THEIR  EFFECT 


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CHAPTER   III 
PAINT  PIGMENTS  AND  THEIR  PROPERTIES 

FOR  the  student  of  paint  technology,  who  is  not  already  ac- 
quainted with  the  chemistry  and  physics  of  the  various  raw 
pigments  which  are  largely  used  in  the  manufacture  of  paints, 
the  writer  advises  a  careful  reading  of  this  chapter,  in  which  the 
matter  has  been  condensed  as  much  as  possible.  In  order  to 
more  thoroughly  acquaint  the  reader  with  the  physical  con- 
stitution of  the  pigments  under  consideration,  there  has  been 
included  photomicrographs,  which  show  to  advantage  the 
structure  of  each.1 

Basic  Carbonate-White  Lead.  This  pigment  is  made  by 
stacking  clay  pots  containing  dilute  acetic  acid  and  lead  buckles, 


By  Polarized  Light  By  Transmitted  Light 

Basic  Carbonate- White  Lead 

in  tiers,  and  covering  them  with  tan  bark.  Fermentation  of 
the  tan  bark,  with  subsequent  formation  of  carbon  dioxide 
acting  on  the  acetate  of  lead  formed  within  the  pots,  produces 
basic  carbonate  of  lead.  After  complete  corrosion,  the  white 
lead  is  ground,  floated,  and  dried.  Corroded  white  lead  has  a 
specific  gravity  of  6.8  and  contains  about  85%  lead  oxide  and 

1  The  author  gratefully  acknowledges  the  assistance  of  Dr.  J.  A.  Schaeffer 
in  the  preparation  of  the  photomicrographs  shown  in  this  chapter. 

42 


PAINT  PIGMENTS  AND   THEIR  PROPERTIES 


43 


15%  of  carbon  dioxide  and  water.  Its  opaque  nature  and 
excellent  body  renders  it  extremely  valuable  as  a  constituent 
of  paints.  Checking  and  chalking  progress  rapidly  when  the 


Crystals  of  Cerussite  in  Old  Dutch  Process  White 
Lead.     (Greatly  magnified) 


White  Lead  (Quick  Process) 

pigment  is  used  alone.  The  various  sized  particles,  both  large 
and  small,  resulting  from  the  corrosion  process,  are  prominently 
shown  in  the  photomicrograph. 

On  account  of  its  alkaline  nature,  this  pigment  acts  upon  the 
saponifiable  oil  in  which  it  is  ground,  forming  lead  soaps  which 


44 


PAINT  TECHNOLOGY  AND  TESTS 


accelerate  chalking  of  white  lead  —  the  greatest  evil  attending 
its  use.  Solubility  in  carbonic  acid  of  the  atmosphere  and 
decay  in  the  presence  of  sodium  chloride  may  be  active  causes 


Corrosion  cylinders  used  for  making  Quick  Process  White  Lead 


Lead  Melting  Pots 

of  the  rapid  chalking  of  this  pigment  at  the  seashore.  Checking 
in  some  climates  appears  to  proceed  rapidly  on  white  lead  paints, 
in  a  deep  hexagonal  form,  leaving  a  series  of  rough  crests  and 
cracks.  This  checking  is  secondary  to  the  chalking  which  takes 
place. 


PAINT    PIGMENTS  AND    THEIR  PROPERTIES 


45 


White  Lead  (Quick  Process).  By  acting  on  atomized  metallic 
lead,  contained  within  large  revolving  wooden  cylinders,  with  dilute 
acetic  acid  and  carbon  dioxide,  the  quick-process  white  lead  is 


Sheet  iron  box  luted  at  bottom  with  water.  Atomized  lead, 
blown  into  box  with  steam,  falls  to  bottom  and  becomes 
hydrated  (Mild  Process) 


Photographs  courtesy  of  Stowe  Neal 

View  of  agitation  tanks  for  making  Mild  Process  Lead 

produced.    Its  value  is  equal  to  the  Dutch-process  white  lead,  and 
it  is  considered  by  some  as  possessing  greater  spreading  value. 


46  PAINT  TECHNOLOGY  AND   TESTS 

White  Lead  (Mild  Process).  The  Mild  Process  of  manu- 
facturing white  lead  consists  of  first  melting  the  pig  lead  and 
converting  it  into  the  finest  kind  of  lead  powder,  then  mixing  thor- 
oughly with  air  and  water.  The  lead  takes  up  water  and  oxygen 
and  forms  a  basic  hydroxide  of  lead.  Carbon  dioxide  gas  is 
next  pumped  slowly  through  the  cylinders  which  contain  the 
basic  hydroxide  of  lead.  The  result  is  basic  carbonate  of  lead  — 
the  dry  white  lead  of  commerce.  The  process  is  called  "  Mild  " 
because  it  is  the  mildest  process  possible  for  the  manufacture  of 
white  lead.  It  is  the  only  method  in  practical  operation  which 


Steam  Jected  Pans  for  Drying  White  Lead 

does  not  require  the  use  of  acids,  alkalis  or  other  chemicals, 
every  trace  of  which  should  be  removed  from  the  finished  product 
by  expensive  purifying  processes.  The  failure  of  such  washing 
and  purifying  means  a  product  of  inferior  quality,  which  neces- 
sarily reduces  the  durability  of  any  paint  in  which  it  is  used. 

Basic  Sulphate- White  Lead  (Sublimed  White  Lead).  By 
the  action  of  the  oxygen  of  the  air  on  the  fume  produced  by  the 
roasting  and  subsequent  volatilization  of  galena,  this  fine,  white, 
amorphous  pigment  is  made.  On  analysis,  its  composition 
shows  approximately  75%  of  lead  sulphate,  20%  of  lead  oxide, 
and  5%  of  zinc  oxide.  It  has  a  specific  gravity  of  6.2. 


PAINT  PIGMENTS  AND   THEIR  PROPERTIES 


47 


Possessed  of  extreme  stability,  it  finds  wide  use  as  a  constituent 
of  paints  and  as  a  base  for  tinting  colors.  The  photomicrograph 
of  this  pigment  shows  its  extremely  fine,  amorphous  nature 
with  complete  absence  of  crystals.  In  fineness  it  closely 
approaches  zinc  oxide.  On  account  of  its  non-poisonous 
properties  it  is  replacing  corroded  lead  in  many  places.  Unified 
paints  containing  sublimed  white  lead  are  of  great  value,  show- 
ing upon  long  exposure  very  little  decay. 


View  of  Furnace  for  Making  Sublimed  White  Lead 

Sublimed  Blue  Lead.  Sublimed  blue  lead  is  made  by  burning 
coarsely  broken  lumps  of  galena,  admixed  with  bituminous  coal, 
in  a  special  form  of  furnace.  The  fumes  which  are  volatilized 
from  this  mixture  are  very  complex  in  their  chemical  make-up, 
and  in  color  are  white,  blue,  and  black.  After  being  drawn 
through  the  cooling  pipes  by  the  suction  of  huge  fans,  whereby 
the  fumes  are  cooled,  the  pigment  is  deposited  in  bags.  This 
pigment  is  bluish  black  in  color,  and  has  been  highly  recom- 


View  of  Goosenecks  Used  for  Collecting  Sublimed  White 
Lead  Fume 


Bag   Room  Where  Sublimed  White  Lead 
is  Deposited 

Photographs  courtesy  of  Picker  Lead  Co. 


PAINT  PIGMENTS  AND   THEIR  PROPERTIES 


49 


mended  for  use  on  iron  and  steel.     Its  composition  runs  approxi- 
mately as  follows: 

Lead  sulphate 50% 

Lead  oxide    35% 

Lead  sulphide 5% 

Lead  sulphite   5% 

Zinc  oxide   2% 

Carbon     3% 

The  color  of  the  pigment  is  largely  due  to  the  carbon  and  the 
lead   sulphide.      Its   specific   gravity   is   6.4,   and   it   grinds    in 


Sublimed  White  Lead 

10%  of  oil  to  a  stiff  paste,  100  Ibs.  of  which  may  be  thinned 
with  about  26  Ibs.  of  oil  to  working  consistency.     Paint  manu- 


View  of  largest  Zinc  Oxide  Works  in  America,  at  Hazards,  Pa. 

facturers  use  it  in  mixture  with  iron  oxide  and  other  pigments 
for  the  production  of  paints  for  metal  surfaces.  Wood  and 
others  have  found  it  of  great  value  for  this  purpose.  It  has  a 


50 


PAINT   TECHNOLOGY  AND   TESTS 


View  of  Zinc  Oxide  Furnaces 


Photographs  courtesy  Ceo.  B.  Heckel  and  N.  J.  Zinc  Co. 

View  of  Zinc  Oxide  Fume  Pipes  with 
electrically  driven  Suction  Fans 


PAINT  PIGMENTS  AND  THEIR  PROPERTIES 


51 


tendency  to  chalk,  but  this  may  be  overcome  by  admixture 
with  other  pigments  such  as  zjnc  oxide  and  iron  oxide.  Lane 
has  found  it  to  be  very  durable  when  admixed  with  lampblack. 
Zinc  Oxide.  This  extremely  wrhite  and  fine  pigment  is  pre- 
pared by  the  roasting  and  sublimation  of  franklinite,  zincite, 
and  other  zinc-bearing  ores  largely  found  in  New  Jersey.  Its 
purity  approaches  in  most  instances  99.5  or  more.  It  has  a 


View  of  Bag  Room  receiving  Zinc  Oxide 

specific  gravity  of  5.2.  On  account  of  its  stability,  whiteness, 
and  opacity,  it  is  invaluable  as  a  pigment  when  a  constituent 
in  a  combination  formula.  Its  extreme  hardness  renders  it  less 
resistant  to  temperature  changes,  when  used  alone.  Under  the 
microscope  the  fineness  and  structure  of  the  particles  are  clearly 
evident.  The  French-process  zinc  oxide  produced  in  America 
by  the  sublimation  and  oxidation  of  spelter  is  the  purest  made, 
and  superior  to  imported  grades  which  often  contain  ultra- 
marine blue  as  a  whitening  agent. 

Zinc  Lead  White.     This  extremely  fine  pigment,  consisting 
of  about  equal   parts  of  zinc  oxide  and  lead  sulphate,   results 


Zinc  Lead.     By  transmitted  light 
(The  Pigment  shows  black) 


Lithopone 


Magnesium  Silicate  (Asbestine) 


PAINT  PIGMENTS  AND  THEIR  PROPERTIES 


53 


from  the  reduction,  volatilization  and  subsequent  oxidation  of 
sulphur-bearing  lead  and  zinc  ores.  It  has  a  specific  gravity  of 
4.4.  Its  slightly  yellowish  tint  bars  it  from  being  used  alone 
very  extensively,  but  when  mixed  with  white  lead,  zinc  oxide 
and  inert  pigments,  or  used  as  a  base  for  colored  paints,  it  is  of 
considerable  value.  The  magnification  of  the  particles  shows 


Asbestine  Mine  at  Easton,  Pa. 

the  peculiar  way  in  which  the  pigment  agglomerates,  and  the 
characteristics  of  a  fine,  uniform  pigment. 

Lithopone.  Lithopone,  probably  the  whitest  of  pigments, 
results  from  the  double  decomposition  of  zinc  sulphate  and 
barium  sulphide,  thereby  forming  a  molecular  combination  of 
zinc  sulphide  and  barium  sulphate.  The  peculiar  property  which 
it  possesses,  of  darkening  under  the  actinic  rays  of  the  sun, 
makes  it  essential  that  it  be  combined  with  other,  more  stable 
pigments  to  prolong  its  life  when  exposed  to  weather.  Litho- 
pone contains  approximately  70%  barium  sulphate,  .25  to 
28%  zinc  sulphide,  and  as  high  as  5%  of  zinc  oxide.  Its 
specific  gravity  is  about  4.25.  It  is  excellently  suited  for 
interior  use  in  the  manufacture  of  enamels  and  wall  finishes. 
When  properly  mixed  with  other  pigments,  such  as  zinc  oxide 
and  calcium  carbonate,  fair  results  are  obtained  as  a  pigment 


54 


PAINT   TECHNOLOGY  AND   TESTS 


American  Barytes.     Transmitted  light 
(The  Pigment  shows  black) 


German  Barytes.     Mag.  250  Diam. 

(The  Pigment  shows  white) 


PAINT  PIGMENTS  AND   THEIR  PROPERTIES  55 

for  outside  work.  Lead  pigments  are  never  used  with  lithopone, 
as  lead  sulphide  results,  giving  a  black  appearance.  Its  char- 
acteristic flocculent,  non-crystalline  nature  is  plainly  evident 
when  examined  under  the  microscope. 

Magnesium  Silicate  (Asbestine  and  Talcose).  This  pig- 
ment comes  in  two  forms:  as  asbestine  and  as  talcose  (talc,  etc.). 
The  former  is  very  fibrous  in  nature  and  is  a  very  stable  pigment 
to  use  in  the  manufacture  of  paint,  on  account  of  its  inert  nature 
and  tendency  to  hold  up  heavier  pigments,  and  prevent  settling. 
It  also  has  the  property  of  strengthening  a  paint  coat  in  which 
it  is  used.  The  talcose  variety  is  very  tabular  in  form.  Both 


By  Polarized  Light  By  Transmitted  Light 

Barium  Sulphate  (Barytes) 

varieties  are  transparent  in  oil,  and  very  inert.     They  have  a 
gravity  of  about  2.7  and  grind  in  about  32%  of  oil. 

Barium  Sulphate  (Barytes).  By  grinding  the  crude  ore, 
treating  with  acid  to  remove  the  iron,  and  finally  washing, 
floating,  and  drying,  there  is  produced  the  commercial  form  of 
this  valuable  pigment.  It  is  used  in  large  quantity  as  a  base 
upon  which  to  precipitate  colors,  and  also  together  with  other 
white  pigments  in  the  manufacture  of  ready-mixed  paints.  It 
renders  the  paint  coating  more  resistant  to  abrasion,  and  gives 
to  the  paint  certain  very  important  brushing  qualities.  It  is  a 
very  stable  pigment,  not  being  materially  affected  by  either  acid 
or  alkali,  and  can  be  used  with  the  most  delicate  colors.  In 
oil  it  is  transparent  and  must  be  mixed  with  opaque  pigments 


56 


PAINT   TECHNOLOGY  AND   TESTS 


Barium  Carbonate.     Mag.  250  Diam. 
(The  Pigment  shows  white) 


. 


V^ 


Barium  Sulphate  (Blanc  Fixe) 


Calcium  Carbonate  (Whiting) 


PAINT  PIGMENTS  AND   THEIR  PROPERTIES 


57 


Calcium  Carbonate.     By  transmitted  light 
(The  Pigment  shows  black) 


Calcium  Sulphate.     By  transmitted  light 
(The  Pigment  shows  black) 


58  PAINT   TECHNOLOGY  AND   TESTS 


Calcium  Sulfate 


Calcium  Sulphate  (Gypsum)  Silica  (Silex) 


PAINT   PIGMENTS  AND   THEIR  PROPERTIES  59 


Silex.     Mag.  250  Diam. 
(The  Pigment  shows  white) 


China  Clay.     By  transmitted  light 
(The  Pigment  shows  black) 


60  PAINT  TECHNOLOGY  AND   TESTS 

when  used  in  ready-mixed  paints.  It  is  generally  used  with 
lighter  pigments,  such  as  asbestine,  in  order  to  prevent  settling. 
Under  the  microscope,  both  by  polarized  and  transmitted  light, 
the  sharp  angles  of  the  particles  appear  distinctly,  with  no  ten- 
dency to  mass  into  a  compact  form.  Although  transparent 
in  oil,  it  is  valuable  in  moderate  percentage  in  a  ready-mixed 
paint. 

Barium  Sulphate  (Blanc  Fixe).  Blanc  fixe  is  the  precipitated 
form  of  barium  sulphate,  resulting  from  the  action  of  soluble 
barium  salts  on  soluble  sulphates.  The  specific  gravity  (4.2) 
of  this  compound  is  lower  than  that  of  barytes.  Possessing 
greater  opacity  in  oil,  it  is  of  more  value  as  a  paint  pigment  for 
some  purposes.  It  comes  in  for  its  greatest  use  as  a  base  on 
which  to  precipitate  lake  colors.  The  very  fine  particles  show 
a  slight  tendency  to  agglomerate. 

Calcium  Carbonate  (Whiting).  The  natural  form  of  calcium 
carbonate,  prepared  from  chalk,  has  a  much  higher  specific 
gravity  (2.74)  than  that  of  the  artificial  form  (2.5)  prepared  by 
the  precipitation  of  calcium  carbonate.  The  latter,  however, 
possesses  greater  hiding  properties.  Both  grades  find  a  wide 
use  in  distemper  work  and  in  the  manufacture  of  putty.  It  is 
often  used  in  small  percentage  in  many  ready-mixed  paints. 
The  photomicrograph  of  the  pigment  shows  the  presence  of 
many  large  particles. 

Calcium  Sulphate  (Gypsum).  The  mineral  gypsum,  con- 
sisting of  calcium  sulphate  and  about  21%  of  water  of  combi- 
nation, is  sometimes  used  as  a  paint  pigment  after  grinding 
and  dehydration.  Being  slightly  soluble  in  water  it  has  a 
tendency  to  pass  into  solution  when  exposed  to  atmospheric 
agencies.  It  lacks  hiding  power  in  oil.  Its  specific  gravity  is 
.2.3.  As  in  the  case  of  all  pigments  prepared  directly  from 
mineral  substances,  the  many-sized  and  shaped  particles  appear 
clearly  when  enlarged.  Partially  and  wholly  dehydrated  forms 
of  gypsum  are  also  used  in  paint. 

Silica  (Silex.)  This  white  pigment  possesses  great  tooth  and 
spreading  properties.  It  is  of  use  as  a  wood  filler  and  as 
a  constituent  in  combination  paints.  It  wears  especially  well 
when  used  in  combination  with  zinc  oxide  and  white  lead.  Its 
purity  often  approaches  97%.  The  particles  when  enlarged 
are  seen  to  have  sharp  angles  and  are  not  uniform  in  size, 
which  accounts  for  its  marked  tooth  and  properties. 


PAINT    PIGMENTS    AND    THEIR    PROPERTIES          61 


Aluminum  Silicate  (China  Clay) 


Raw 


Sienna 


Burnt 


I 


.*!•  * 


Raw 


Burnt 


Umber 


62  PAINT   TECHNOLOGY  AND   TESTS 

Aluminum  Silicate  (China  Clay).  China  clay,  or  aluminum 
silicate,  is  a  permanent  and  valuable  white  pigment  showing 
very  little  hiding  power  in  oil.  It  is  found  widely  distributed 
in  granitic  formations.  It  is  very  stable,  with  a  gravity  of  2.6. 
Particles  are  found  in  many  shapes  and  sizes,  showing  sharp 
and  definite  angles. 

Ochre.  Ochre  is  a  hydrated  ferric  oxide  permeating  a  clay 
base,  largely  used  as  a  tinting  material.  It  has  a  specific  gravity 
of  about  3.5,  and  a  decidedly  golden  yellow  color.  A  good 
quality  should  contain  20%  or  over  of  iron  oxide.  The  par- 
ticles of  this  pigment  are  flocculent  and  very  uniform  in 
appearance. 

Sienna.  Sienna,  like  umber,  is  essentially  a  silicate  of  iron 
and  alumina,  containing  manganic  oxide.  It  contains,  however, 
a  lower  percentage  of  the  latter  than  in  the  case  of  umbers.  The 
photomicrograph  of  the  burnt  variety  shows  clearly  the  fine 
condition  of  the  pigment,  while  large  particles  are  shown  in  the 
raw  variety. 

Umber.  Umber,  another  naturally  occurring  pigment,  con- 
sists of  iron  and  aluminum  silicates,  containing  varying  propor- 
tions of  manganic  o~xide,  its  color  and  tone  varying  according 
to  the  percentage  of  the  latter.  The  raw  variety  is  drab  in 
color,  which  in  burning  changes  to  reddish  brown.  A  marked 
percentage  of  large-sized  particles  exist  in  this  pigment. 

Indian  Red.  Indian  red  is  the  term  applied  to  natural  hema- 
tite ore  pigments  and  to  those  produced  by  the  roasting  of 
copperas  (iron  sulphate).  They  generally  contain  95%  or 
more  of  iron  oxide,  with  varying  percentages  of  silica.  The 
pigment  is  heavier  (specific  gravity  5.2)  than  that  of  Metallic 
Brown.  The  crystalline,  mineral-like  structure  of  the  particles 
differ  greatly  from  the  amorphous  particles  of  Metallic  Brown. 

Metallic  Brown.  The  natural  hydrated  iron  oxide  or  carbonate 
as  mined  largely  in  Pennsylvania,  yields,  when  roasted,  a  ses- 
quioxide  of  iron  known  as  Metallic  Brown.  It  contains  a  high 
percentage  of  alumina  and  silica,  and  has  a  characteristic  brown 
color  with  a  gravity  of  3.1.  It  finds  wide  application  as  a  pig- 
ment for  protective  purposes.  The  particles  when  enlarged 
show  the  usual  appearance  of  a  natural  compound  which  has 
been  roasted  and  ground. 


PAINT  PIGMENTS  AND   THEIR  PROPERTIES 


63 


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64  PAINT   TECHNOLOGY  AND   TESTS 

Analysis  of  Iron  Oxide  Pigments.  Because  of  the  great 
consideration  now  being  given  to  iron  oxide  paints,  the  writer 
secured  a  series  of  oxides  widely  used  in  this  country,  and  has 
determined  the  most  important  constituents  of  each. 

Basic  Lead  Chromate  (American  Vermilion).  By  boiling 
white  lead  with  chromate  of  soda  and  subsequently  treating  with 
small  quantities  of  sulphuric  acid,  American  vermilion,  or  basic 
lead  chromate,  is  prepared.  It  contains  98%  of  lead  com- 
pounds, frequently  free  chromates,  and  has  a  gravity  of  6.8. 
The  particles  appear  granular  and  large,  frequently  assuming 
a  square  structure. 

Red  Lead.  By  the  continued  oxidation  of  litharge  in  rever- 
beratory  furnaces,  red  lead  is  produced  as  a  brilliant  red  pig- 
ment with  a  specific  gravity  of  8.7.  The  pigment  particles 
appear  to  be  of  many  sizes,  showing  a  slight  tendency  to  form  a 
compact  mass. 

Paranitraniline  Red.  Paranitraniline  red,  a  very  bright  red 
material  largely  used  in  tinting  paints,  is  prepared  by  diazotizing 
paranitraniline  in  hydrochloric  acid  by  means  of  sodium  nitrite 
in  the  cold.  This  compound  is  rendered  insoluble  when  pre- 
cipitated directly  on  barytes,  by  acting  on  it  with  an  alkaline 
solution  of  beta  naphthol.  It  is  the  most  stable  and  permanent 
bright  red  organic  pigment  which  the  paint  manufacturer  uses. 
The  particles  of  this  pigment  appear  in  various  sizes,  due,  no 
doubt,  to  a  massing  of  the  particles  in  the  precipitation  process. 

Chrome  Yellow.  The  neutral  chromate  of  lead,  made  from 
either  the  nitrate  or  acetate  of  lead  and  chromate  of  soda,  finds 
wide  use  as  a  tinting  pigment.  When  precipitated  on  a  white 
pigment  base,  various  trade  names  are  given  to  it.  The  micro- 
scope shows  clearly  the  physical  character  of  this  pigment. 

Zinc  Chromate.  This  pigment  is  made  either  from  zinc  salts 
and  bichromate  of  potash  or  zinc  oxide  heated  with  chrome 
salts,  frequently  in  the  presence  of  acid.  Like  the  rest  of  the 
chromate  pigments,  it  is  a  very  slow-drying  material,  often  re- 
quiring over  a  week  to  set  up,  unless  considerable  drier  is  added. 
In  spite  of  the  impurities  which  it  carries,  it  has  shown  itself 
to  be  one  of  the  most  inhibitive  pigments  known  and  has 
demonstrated  its  value  in  even  small  percentages  in  paints  for 
iron  and  steel.  It  dries  to  a  hard  adherent  film  that  tends  to 
protect  metal  from  corrosion. 


PAINT    PIGMENTS    AND    THEIR  PROPERTIES  65 


ML 

*Vi 


Indian  Red 


^H 

Metallic  Brown 


'iji^i 


Basic  Lead  Chromate    (American  Ver- 
milion) 


Red  Lead 


Paranitraniline 


Chrome  Yellow 


66  PAINT  TECHNOLOGY  AND   TESTS 

Prussian  Blue.  On  oxidizing  the  precipitate  resulting  from 
the  interaction  of  solutions  of  prussiate  of  potash  and  copperas 
(iron  sulphate),  Prussian  blue  as  used  in  the  paint  trade  is  pre- 
pared. It  has  a  specific  gravity  of  1.9.  The  pigment  shows 
an  amorphous  structure,  the  particles  varying  greatly  in  size. 

Ultramarine  Blue.  This  bright  blue  pigment  is  prepared  by 
burning  silica,  china  clay,  soda  ash  and  sulphur  in  pots  or  fur- 
naces. It  has  a  specific  gravity  of  2.4.  It  is  of  little  value  as 
a  paint  pigment  on  account  of  its  sulphur  content,  which  causes 
darkening  when  mixed  with  lead  pigments,  and  corrosion  when 
applied  to  iron  or  steel.  The  darkness  of  the  photograph  is  due 
to  the  massing  of  the  pigment  particles. 

Chrome  Green.  Chrome  green  is  prepared  as  a  paint  pigment 
from  nitrate  of  lead,  Chinese  blue,  and  bichromate  of  soda. 
It  has  a  gravity  of  4  and  is  liable  to  contain  slight  traces  of  lead 
salts.  The  particles  when  magnified  appear  very  fine  and 
flocculent.  This  color  is  often  precipitated  on  pigments,  such 
as  barytes,  which  do  not  reduce  its  tone. 

Bone  Black.  By  grinding  the  carbonaceous  matter  resulting 
from  the  charring  of  bones,  in  iron  retorts,  the  pigment  bone 
black  is  prepared.  It  contains  about  15%  of  carbon  and 
85%  of  calcium  phosphate.  It  has  a  gravity  of  2.7.  Com- 
paratively large  particles  of  charred  bone  can  be  seen  scat- 
tered throughout  the  mass,  resulting  from  the  difficulty  of 
grinding  to  a  uniform  size. 

Carbon  Black.  This  form  of  very  pure  carbon  results  from 
the  combustion  of  gas.  Its  gravity,  1.09,  is  lower  than  that 
of  lampblack,  which  shows  a  gravity  of  1.8.  It  is  used  in 
much  the  same  way  and  for  the  same  purposes  as  lampblack. 
In  physical  appearance  it  shows  great  similarity  to  the  particles 
of  lampblack. 

Lampblack.  This  pigment,  made  from  the  combustion  of 
oils,  consists  very  often  of  more  than  99%  carbon.  It  has 
wonderful  tinting  value.  The  particles  show  a  fine,  fibrous 
structure  with  a  tendency  toward  agglomeration.  They  differ 
greatly  in  physical  appearance  from  those  of  either  graphite  or 
bone  black,  being  exceedingly  more  uniform  than  the  latter. 

Graphite.  Graphite,  both  in  the  natural  and  artificial  form, 
contains  impurities  such  as  silica,  iron  oxide  and  alumina,  but 
the  natural  form  has  a  much  greater  percentage  of  these  foreign 


PAINT    PIGMENTS    AND    THEIR    PROPERTIES          67 


--  ft 


-  f  .' 


Zinc  Chromate 


Prussian  Blue 


Ultramarine  Blue 


Chrome  Green 


Bone  Black 


Carbon  Black 


68 


PAINT  TECHNOLOGY  AND   TESTS 


materials,  in  some  cases  as  high  as  40%.  Graphite  is  usually 
mixed  with  other  pigments,  such  as  red  lead  and  sublimed  blue 
lead,  thus  serving  better  as  a  paint  coating.  The  difference 
in  physical  appearance  of  the  various  carbon  pigments  is  inter- 
esting, as  each  pigment  has  characteristics  of  its  own.  In 
graphite  we  find  a  great  tendency  toward  agglomeration  or 
massing  of  particles. 

Mineral  Black.  Mineral  black  is  a  pigment  made  by  grinding 
a  black  form  of  slate.  It  contains  a  comparatively  low  per- 
centage of  carbon  and  consequently  has  low  tinting  value.  It 
finds  use  as  an  inert  pigment  in  compounded  paints,  especially 
for  machine  fillers.  The  pigment  has  a  flocculent  appearance, 
the  particles  showing  a  strong  tendency  to  mass. 

Photomicrographs  of  two  combination  paint  pigments  are 
here  given,  to  show  the  various  pigments  as  they  appear  under 
the  microscope,  when  in  combination. 

PERCENTAGES  OF  OIL   REQUIRED    FOR    GRINDING    VARIOUS 
DRY  PIGMENTS  INTO  AVERAGE  PASTE  FORM 


White  lead  (corroded)    

White  lead  (sublimed) 

Zinc  lead  (American) 

French  process  zinc  oxide 

American  process  zinc  oxide  .  . 

Blanc  fixe 

Barytes  (natural)    

Paris  white  (whiting)   

Terra  alba  (gypsum)    

Floated  silica  or  Silex 

Kaolin  (China  clay) 

Asbestine     

Blue,  ultramarine 

Blue,  Chinese  or  Prussian   .... 

Black,  gas  carbon   

Black,  lamp 

Black,  drop    

Black,  bone   

Brown,  mineral 

Brown,  Vandyke   

Chrome  yellow,  lemon 

Chrome  yellow,  medium 

Chrome  yellow,  orange    

Chrome  yellow,  dark  orange  .  . 

Chrome  green,  Chem.  pure  light 

Chrome  green,  Chem.  pure  ex- 
tra dark 

Chrome  green,  25%,  color  light 

Chrome  green,  25%,  color  extra 
dark 


9% 
10% 

12% 
17% 
16% 
30% 
9% 
20% 
22% 
26% 
28% 
32% 
27% 
50% 
82% 
72% 
60% 
50% 
24% 
50% 
23% 
30% 
20% 
15% 
21% 

25% 
13% 

17% 


Graphite  (pure) 40% 

Indian  red,  (98%)    20% 

Ochre,  yellow,  American 26% 

Ochre,  yellow,  French 28% 

Ochre,  golden 28% 

Red,  Venetian 23% 

Red,  Oxide     25% 

Red,  Tuscan    27% 

Red,  Turkey 28% 

Red,  lead    12% 

lied,  lake 55% 

Sienna,  Italian,  raw 52% 

Sienna,  Italian,  burnt 45% 

Sienna,  American,  burnt 38% 

Sienna,  American,  raw 40% 

Ultramarine  green 28% 

Umber,  Turkey,  raw 48% 

Umber,  Turkey,  burnt 47% 

Umber,  American,  burnt 36% 

Umber,  American,  raw 38% 

Verona  green    (terra   verte   or 

green  earth)   32% 

Vermilion,  English  (quicksilver)  14% 
Vermilion,    American    (chrome 

red)  16% 

Paris  green,  American 23% 

Zinc  chromate  (permanent  yel- 
low)     15% 


PAINT    PIGMENTS    AND    THEIR    PROPERTIES  69 


Lampblack 


Graphite 


Mineral  Black 


Asbestine  and  Whiting 


Silica  and  Asbestine 


CHAPTER   IV 
PHYSICAL  LABORATORY  PAINT  TESTS 

FOR  the  paint  chemist  who  desires  to  familiarize  himself  with 
the  more  recent  analytical  methods  worked  out  in  American 
laboratories,  reference  may  be  had  to  treatises  on  the  analysis 
of  paints,  by  Gardner  and  Schaeffer,1  and  Holley  and  Ladd.2 
Analytical  methods  are  not  included  in  this  chapter,  the  writer's 
desire  being  to  treat  the  subject  from  the  standpoint  of  the  physi- 
cal properties  of  painting  materials.  The  work  outlined  herein 
is  of  a  nature  that  affords  a  wide  field  of  research,  and  a  brief 
study  will  doubtless  suggest  similar  work  to  the  student  of  paint. 

Preparation  of  Paint  Films.  The  study  of  paint  films  is  one 
that  has  become  of  vital  importance,  and  is  receiving  at  the 
present  time  great  attention.  Among  the  many  methods  which 
have  been  suggested  and  attempted  for  securing  paint  films,  a 
few  already  well  known  may  be  mentioned. 

By  painting  upon  zinc  and  eating  away  the  zinc  with  acid: 
The  objection  to  this  method  is  very  evident,  namely,  the  action 
of  the  acid  upon  the  paint  coating,  which  is  likely  to  be  very 
severe.  Another  method  has  been  to  spread  paraffin  on  a  glass 
plate,  and  painting  upon  this  surface.  When  the  paint  is  dried, 
the  paraffin  is  melted  off  and  thus  the  film  is  obtained.  This 
method  is  open  to  objections,  in  that  the  paraffin  surface  is  not 
a  comparable  one  upon  which  to  paint,  and  also  that  the  complete 
removal  of  the  paraffin  is  not  assured. 

Another  method  consists  in  covering  a  piece  of  glass  with  tin 
foil,  painting  out  the  film  upon  the  foil,  and  after  drying  properly, 
to  remove  the  sheet  of  foil  with  its  coating  of  paint  and  immerse 
in  a  bath  of  mercury  which,  by  amalgamation  of  the  tin,  leaves 
the  paint  film. 

1  The  Analysis  of  Paints  and  Painting  Materials.      McGraw-Hill  Book 
Co.,  New  York,  1910. 

2  Mixed  Paints,   Color  Pigments  and  Varnishes.      John  Wiley  &  Sons, 
New  York,  1908. 

70 


PHYSICAL  LABORATORY  PAINT  TESTS  71 

We  now  come  to  a  method  worked  out  in  our  laboratories,  which 
can  be  recommended  as  being  not  only  simple  but  efficient  and 
practical.  It  has  been  found  that  a  size  from  noodle  glue,  when 
painted  upon  ordinary  fair-quality  paper,  makes  a  surface  from 
which  the  paint  may  be  subsequently  stripped.  The  paint  is 
applied  in  the  ordinary  way  to  the  paper,  which  is  held  during 
the  operation  by  thumb  tacks,  and  allowed  to  dry.  The  paint 
may  be  separated  by  immersion  in  water  kept  at  about  50  degrees 
Centigrade.  By  this  method  large  films  may  be  obtained,  but  it 
has  been  found  very  unhandy  to  work  with  films  exceeding  an 


Bottles  Showing  Relative  Permeability  of  Films  by  Amount  of  Whit- 
ing Formed  Within 

area  of  eight  inches  square.  When  the  film  of  paint  has  been 
detached  from  the  sized  paper  through  the  dissolving  of  the 
noodle  glue,  the  paint  film  is  then  immersed  in  a  fresh  solution 
of  water,  in  order  to  remove  whatever  excess  of  noodle  glue  there 
may  be  remaining.  A  glass  rod  is  then  introduced  into  the 
bath,  in  which  the  paint  film  is  floated  upon  the  glass  rod,  which 
is  then  hung  up  to  dry  in  a  suitable  container  to  prevent  the 
accumulation  of  dust,  e^c. 

The  Permeability  of  Paint  Films.  A  series  of  tests  were  made 
to  determine  the  water-excluding  values  of  various  combinations 
of  painting  pigments  ground  in  pure  linseed  oil.  White  pine 
boards,  six  inches  long,  four  inches  wide,  and  one  inch  thick,  were 


72  PAINT  TECHNOLOGY  AND   TESTS 

carefully  prepared  and  numbered  and  given  three  coats  of  a  white 
paint  formula  of  the  corresponding  number.  After  drying,  the 
boards  were  carefully  weighed  and  immersed  in  a  tub  of  water 
for  three  weeks.  After  removal,  the  surfaces  of  the  boards  were 
dried  with  blotting  paper  and  the  boards  weighed.  The  gain 
in  weight,  corresponding  to  the  amount  of  water  penetrating 
through  the  pores  of  the  wood,  was  observed.  The  boards  were 
again  immersed  and  at  the  end  of  two  months  the  following 
results  were  obtained: 

Grammes  of  water 

Formula  absorbed 

No.  through  paint 

1.  Soya  bean  oil    120 

2.  Linseed  oil     102 

3.  Calcium  sulphate  93 

4.  Barytes 88 

5.  Asbestine  74 

6.  Corroded  white  lead     59 

Basic    carb.  —  White  lead  25% 
Basic  sulph.  —  WThite  lead  20% 


7.    ^  Zinc  oxide  .  .  .25^ 


58 


Calcium  sulphate    25% 

Calcium  carbonate    5% 

8.  Sublimed  white  lead    56 

9.  Zinc  oxide   56 

f  Zinc  lead  white    30%  ] 

-,  n     j  Zinc  oxide 40%  ' 

'    I  Basic  carb.  —  White  lead   20% 

[  Calcium  carbonate    10% 

1 1      j  Basic  carb.  —  White  lead     50% 

1    I  Zinc  oxide 50% 

f  Basic  carb.  —  White  lead    38%  ] 

12.    «{  Zinc  oxide 48%  [ 38 

[  Silica  14%  J 

The  test  boards  were  then  exposed,  with  their  content  of 
water,  to  the  action  of  the  sun's  rays.  Blistering  of  the  painted 
surfaces  took  place  in  many  cases,  caused  by  the  rapid  with- 
drawal of  the  water  and  its  consequent  action  on  the  paint  film. 
The  tests  seem  to  indicate  that  a  mixture  of  white  lead  and  zinc 
oxide,  with  or  without  a  small  percentage  of  the  inert  pigments, 
is  not  as  subject  to  the  action  of  the  water  as  the  single  pigment 
paints.  In  order,  however,  to  corroborate  these  tests,  it  occurred 
to  the  writer  to  develop  a  more  visible  means  of  demonstrating 
the  passage  of  moisture  through  paint  films. 

Another  series  of  white  pine  boards  were  therefore  soaked  in 
a  solution  of  iron  sulphate  for  several  hours.  After  removal,  the 
surface  of  each  board  was  dried  and  coated  with  one  coat  of  the 


PHYSICAL  LABORATORY  PAINT  TESTS 


73 


Bell  Jar  Apparatus  for  Testing  Permeability  of  Paint  Films 

Paint  films  sealed  over  mouths  of  Bottles  containing  Lime  Water. 
Carbonic  Acid  Gas  generated  under  Bell  Jar  passes  through  Plate 
Films  and  precipitates  Calcium  Carbonate 


74          PAINT  TECHNOLOGY  AND  TESTS 

paints  previously  tested.  After  thorough  drying  for  forty-eight 
hours,  there  was  placed  on  the  surface  of  each  board  a  few  drops 
of  a  solution  of  potassium  ferrocyanide.  This  solution  has  the 
effect  of  producing  a  blue  coloration  with  iron  sulphate,  and  in 
every  case  when  it  was  placed  on  a  paint  of  considerable  porosity, 
the  solution  penetrated  through  and  formed  a  blue  coloration 
beneath  the  paint.  The  results  corroborated  the  original  tests 
referred  to  above. 

A  series  of  sheets  or  films  of  paints  were  then  prepared  accord- 
ing to  the  method  referred  to  on  page  71.  These  films  were 
placed  over  glass  dialyzing  cups,  allowing  the  inner  surfaces  to 
sag  so  as  to  hold  a  small  amount  of  dilute  ammonium  chloride 
solution.  Distilled  water  was  placed  on  the  reverse  side  oi 
the  dialyzing  apparatus  and  the  tests  started.  At  the  end  oi 
six  days  the  distilled  water  in  each  test  was  examined  and  the 
following  results  obtained: 

Test  No.  1  (corroded  white  lead  and  asbestine  film)  allowed 
the  passage  of  0.002  gm.  ammonium  chloride. 

Test  No.  2  (corroded  white  lead  and  zinc  oxide  film)  allowed 
the  passage  of  0.0003  gm.  ammonium  chloride. 

Tests  were  also  made  with  dilute  solutions  of  other  salts  such 
as  ferric  chloride,  having  a  dilute  solution  of  potassium  sulpho- 
cyanide  on  the  reverse  side  of  the  apparatus.  In  the  latter  case 
the  formation  of  a  pink  color,  characteristic  upon  the  mingling 
of  these  solutions,  was  obtained  in  a  few  hours. 

Film-Testing  Machine.  A  film-testing  apparatus,  termed  a 
"  filmometer "  by  its  originator,  Mr.  R.  S.  Perry,  was  con- 
structed, with  the  following  features:  A  graduated  upright 
tube  is  fixed  by  means  of  sealing  wax  to  two  metallic  plates  which 
carry  an  evenly  bored  hole,  exactly  under  the  hole  in  the  up- 
right tube.  This  hole  measures  exactly  one  square  centimeter 
in  area,  and  is  circular.  The  upright  tube  is  graduated  into  lineal 
centimeters  and  is  called  the  pressure  tube. 

Attached  to  the  lower  end  of  this  pressure  tube,  close  to  the 
metallic  plates  which  serve  as  carriers  for  the  paint  film  to  be 
tested,  is  a  side-neck,  which  is  inclined  at  an  angle  of  45  degrees 
to  the  pressure  tube,  and  serves  the  purpose  of  introducing  the 
mercury,  as  will  be  described  later.  Immediately  under  the 
openings  in  the  metallic  plates  which  carry  the  film  are  arranged 
two  pieces  of  iron  inclined  at  a  90-degree  angle,  so  arranged  that 


76  PAINT    TECHNOLOGY    AND    TESTS 


Perry  Film  Testing  Machine 


PHYSICAL  LABORATORY  PAINT  TESTS  77 

when  the  pressure  of  mercury  is  applied  and  causes  rupture  of 
the  film,  the  falling  mercury  shall  be  caught  between  these  two 
insulated  plates  and  cause  contact.  These  two  plates  are  con- 
nected up  by  wire  with  a  pair  of  magnets,  thence  to  an  electric 
bell,  and  from  there  to  storage  batteries  which  supply  the  current. 

A  film  of  paint  is  tested  in  the  following  manner:  A  piece  of 
film  one  inch  square  is  cut  out  and  placed  between  the  two 
metallic  plates  which  hold  the  film  immediately  under  the  pres- 
sure tube.  Mercury  is  run  in  from  a  burette  through  the  side- 
neck  and  applies  pressure  upon  the  film  by  gravity.  As  the 
mercury  is  run  in  it  rises  of  course  in  the  tubes  until  this  pressure 
becomes  so  great  as  to  finally  break  the  film.  At  this  point  the 
mercury  will  run  out,  and,  falling  upon  the  two  insulated  iron 
plates  immediately  below,  will  cause  contact  and  close  the 
circuit  which  rings  an  electric  bell,  which  is  a  signal  for  the  opera- 
tor to  shut  off  the  inflow  of  mercury  through  the  side-neck  from 
the  burette. 

The  pressure  tube  is  also  supplied  with  a  piston  which  is  made 
of  a  piece  of  thin  iron  wire  having  a  disc  attached  to  its  lower 
end.  As  the  mercury  rises  in  the  pressure  tube  this  iron  wire 
is  pushed  up,  being  very  delicately  counterpoised  over  a  wheel. 
Upon  the  breaking  of  the  film  the  mercury  runs  out,  but  upon 
falling  upon  the  two  iron  plates  underneath  causes  contact  to  be 
made,  which  causes  the  current  to  run  through  the  pair  of  magnets 
before  mentioned,  which,  becoming  electrified,  attract  the  piston 
in  the  pressure  tube,  giving  a  reading  for  the  maximum  height 
of  the  column  of  mercury. 

The  supply  of  mercury  being  shut  off,  the  operator  is  now  in 
a  position  to  determine  the  total  sum  of  both  the  elasticity  and 
ductility  of  the  paint  film,  and  also  the  pressure  at  which  the 
film  broke.  The  breaking  pressure  of  course  is  read  directly 
upon  the  pressure  column,  which  is  divided  into  centimeters 
as  has  been  described  above,  the  piston  indicating  the  maxi- 
mum height  of  the  mercury  column.  What  may  be  termed 
the  elasticity  of  the  film  can  now  be  calculated.  As  is  perfectly 
evident,  the  film  in  stretching  does  so  by  distending  from  a  flat 
surface  to  a  curved  or  cup-like  surface.  If  the  pressure  tube  is 
calibrated  in  cubic  centimeters  reckoned  from  a  flat  surface 
where  the  film  was  introduced,  the  stretch  of  the  paint  film  in 
distending  from  a  flat  surface  to  a  curved  surface  may  be  deter- 


78 


PAINT    TECHNOLOGY   AND    TEST 


Diagram  of  Perry  Filmometer 


PHYSICAL  LABORATORY  PAINT  TESTS 


79 


mined.  The  cubic  contents  of  the  pressure  tube  and  side-arm 
become  increased,  owing  to  the  cup-like  shape  the  paint  film 
takes  on.  By  subtracting  the  amount  of  mercury  indicated  by 
the  piston  in  the  pressure  tube  from  the  amount  of  mercury 
delivered  from  the  burette,  tLe  amount  contained  in  the  dis- 
tended paint  film  is  obtained,  wliith  serves  as  a  measure  of  elas- 


Gardner-de  Horvath  film  testing  appa- 
ratus 

ticity.  The  temperature  is  a  most  important  point  to  consider 
in  running  daily  tests  upon  the  filmometer.  The  tests  made  by 
the  writer  were  conducted  at  70  degrees  Fahrenheit  throughout. 
Gardner-de  Horvath  Filmometer.  Another  type  of  filmom- 
eter which  gives  very  concordant  results  was  recently  devised 
by  the  writer  and  de  Horvath.  This  apparatus  is  shown  above. 


80 


PAINT  TECHNOLOGY  AND  TESTS 


It  consists  of  a  three-necked  Wolff  bottle  having  provision 
at  one  of  its  necks  for  exhausting  the  air  from  the  bottle.  The 
reverse  neck  is  provided  with  a  gauged  glass  tube  dipping  into 
a  porcelain  crucible  containing  mercury,  thus  acting  as  a  manom- 
eter. The  middle  neck  is  fitted  to  accommodate  two  ground 
glass  plates.  Both  these  plates  are  provided  with  a  central 
orifice  one  millimeter  in  diameter.  Between  the  plates  is-placed 
a  small  section  of  paint  film.  The  plates  may  be  pressed  together 
or  clamped  together  and  placed  over  the  middle  neck  of  the 
bottle,  a  close  contact  being  made  with  Canada  balsam.  As 
the  air  is  exhausted  from  the  bottle,  the  mercury  in  the  tube 
will  rise  and  continue  in  its  ascent  until  the  film,  which  is 
exposed  to  atmospheric  pressure,  has  offered  it  maximum  resist- 
ance, which  is  shown  by  the  breaking  point.  This  point  is 
observed  on  the  manometer  and  the  result  expressed  in  centi- 
meters of  mercury. 

Table  of  Film  Testing  Results.  By  means  of  the  Perry  film- 
testing  apparatus,  described  in  the  above,  interesting  results  have 
been  obtained,  which  are  embodied  in  the  following  table: 

COMPARATIVE    STRENGTHS    OF    FILMS    AS    OBTAINED    BY    THE    BREAKING 

MACHINE 


No.  Coats 

Pressure 

Thickness 

Stretch 

1. 

Zinc  oxide    

3 

33.2 

0028 

.30 

2. 

Zinc  lead    

3 

32.7 

0034 

.35 

3. 

Asbestine 

3 

28.0 

0045 

15 

4. 

Sublimed  white  lead    

3 

17.9 

0024 

.38 

5. 

Barytes  

3 

13.3 

0042 

.33 

6. 

Lithopone    

3 

13.1 

0024 

.49 

7. 

Whiting    

3 

13.0 

0033 

.32 

8. 

Quick  process  white  lead  .... 

3 

11.3 

0025 

.38 

9. 
10. 

Gypsum   
China  clay      

3 
3 

10.8 
10.8 

0039 
0035 

.29 
.16 

11. 

Silex    

3 

9.6 

0032 

.32 

12. 

Blanc  fixe  

3 

8.5 

0030 

.28 

13. 

Corroded  white  lead  

3 

7.3 

0020 

.33 

14. 

Barium  carbonate  

3 

7.2 

0028 

.16 

By  means  of  this  machine  it  is  possible  to  obtain  very  valuable 
information  concerning  the  effect  of  age  upon  a  paint  as  influ- 
encing its  strength  and  elasticity.  These  are  two  vital  qualities 
in  a  paint,  as  it  is  through  its  strength  that  a  paint  resists  abrasion 
cracking,  peeling,  and  blistering.  That  elasticity  is  a  vital  quali- 


PHYSICAL  LABORATORY  PAINT  TESTS  81 

fication  of  a  paint  may  easily  be  seen  through  the  checking  of 
oil  paintings,  which,  as  Ostwalt  has  pointed  out,  is  due  to  the 
unequal  coefficients  of  expansion  between  the  ground  and  the 
paint.  This  is  particularly  noticeable  in  the  alligatoring  of  many 
enamels  which  contain  large  percentages  of  zinc. 

Curves  have  been  prepared  having  pressure  as  an  abscissa 
and  elasticity  as  ordinate.  These  curves  show  remarkable 
differences  in  different  pigments.  For  instance,  in  the  case  of 
white  lead,  the  curve  takes  a  steep  upward  trend  when  it  ap- 
parently reaches  a  maximum,  the  curve  then  flattening  out  and 
finally  taking  another  steep  upward  trend  just  before  breaking. 
This  may  be  construed  as  follows:  That  under  low  pressures 
the  white  lead  film  is  perfectly  elastic,  when  a  maximum  is 
obtained,  beyond  which  elasticity  does  not  extend.  This  point 
is  the  maximum  point  of  the  upward  trend.  From  here  on 
pressure  may  be  applied  without  any  increase  in  stretch,  this 
being  represented  by  the  flat  part  of  the  curve,  while  the  steep 
upward  trend  just  before  breaking  shows  where  the  paint  begins 
to  tear,  finally  culminating  in  breaking.  In  the  case  of  asbestine, 
however,  the  curve  is  more  of  a  straight  line  up  to  the  breaking 
point,  which  would  go  to  prove  that  elasticity  is  proportionate 
to  pressure  in  the  case  of  this  pigment. 

Moisture  Absorption.  The  structure  of  certain  pigments  is 
such  that  when  they  are  ground  in  linseed  oil  and  painted  out, 
films  are  produced  which  are  very  water-resistant.  This  action 
is  possibly  due  to  the  filling  of  the  voids  in  the  oil,  thus  making 
a  compact  and  water-resistant  film.  Pigments  which  are  coarse 
and  which  present  an  angular  crystalline  structure,  often  produce 
films  which  contain  a  relatively  large  number  of  voids  and  are 
less  waterproof.  Certain  pigments  are  chemically  active  and 
tend  to  produce,  when  ground  in  oil,  metallic  soaps  which  act 
for  a  time  more  or  less  as  varnish  gums,  in  keeping  out  moisture. 
Later  on,  however,  such  films  are  apt  to  break  down  and  admit 
moisture  in  quantity.  The  tests  herein  described  were  designed 
by  the  author  to  determine  the  water-excluding  value  of  a  number 
of  typical  pigments  when  ground  in  linseed  oil  and  painted  out 
into  films.  Unfortunately,  no  method  has  been  devised  by 
which  films  of  the  same  gauge  could  be  prepared.  The  variations 
in  the  thickness  of  the  films  used  in  these  experiments,  however, 
are  not  very  great. 


82 


PAINT   TECHNOLOGY  AND   TESTS 


Apparatus  for  Determining  Excluding  Properties  of  Paint  Films 


PHYSICAL  LABORATORY  PAINT  TESTS 


83 


A  series  of  small  glass  bottles  with  wide  mouths,  holding 
about  two  ounces,  were  half  ^filled  with  concentrated  sulphuric 
acid,  and  paint  films  were  tightly  sealed  over  the  mouths  of  the 
bottles  with  Canada  balsam.  The  bottles  were  then  carefully 
labeled,  numbered,  and  accurately  weighed  upon  chemical  bal- 
ances. Later  they  were  exposed  under  a  large  glass  bell  jar  con- 
taining air  saturated  with  moisture  and  kept  at  a  constant 
temperature.  The  bottles  were  removed  from  the  receptacle 
every  week  and  reweighed.  The  increase  in  weight,  due  to  the 
amount  of  moisture  which  had  penetrated  through  the  films,  and 
absorbed  by  the  sulphuric  acid,  owing  to  its  hygroscopic  nature, 
was  thus  determined.  In  another  series  of  bottles,  lumps  of 
calcium  chloride  were  substituted  for  the  sulphuric  acid.  The 
results  obtained  from  these  tests  correspond  to  those  of  the 
former  tests,  and  led  to  the  conclusion  that  the  porosity  of  lin- 
seed oil  films  varied  when  different  pigments  were  used  in  the  oil. 

MOISTURE  EXPERIMENTS 
Figures  Given  Express  Percentage  Gain  in  Weight,  e.g.,  Water  Absorbed 


7  days 

21  days 

49  days 

White  lead  and  zinc  oxide  . 

0.043% 

0.115% 

0266% 

Zinc  lead  white    .    .                ... 

0.049 

0.130 

0284 

Red  lead  
Sublimed  white  lead  
Zinc  chromate   

0.049 
0.049 
0.064 

0.130 
0.128 
0.176 

0.295 
0.292 
0.417 

Zinc  oxide  . 

0065 

0  172 

0391 

Barytes 

0074 

0202 

0466 

Willow  charcoal 

0077 

0236 

0694 

Lithopone  . 

0.083 

0228 

0550 

Chinese  blue  . 

0092 

0276 

0671 

Natural  graphite  .    . 

0.104 

0.350 

0951 

Ultramarine  

0.119 

0.336 

0.814 

Another  series  of  tests  was  started,  in  which  were  used  films 
prepared  from  various  oils  and  varnishes  made  especially  for 
the  test  from  different  gums.  The  results  of  this  series  are  very 
interesting,  as  they  indicate  that  certain  gums  are  more  powerful 
than  others  in  making  oils  resistant  to  moisture.  The  reader 
should  study  with  care  the  data  on  treated  Chinese  wood  oil, 
most  excellent  results  having  been  obtained  when  it  was  used 
in  the  proper  percentage. 


84 


PAINT  TECHNOLOGY  AND  TESTS 


EXCLUDING     TESTS  ON    OIL    VEHICLES    AND    VARNISHES    SHOWING 
CENTAGE   OF   MOISTURE   ABSORBED   AT   VARIOUS   PERIODS 


PER- 


6  days 

18  days 

24  days 

Linseed  oil,  100%       

.233 

.686 

.895 

Soya  bean  oil.  100%  
Linseed  oil,  80%      \ 

.340 
.250 

1.06 
.755 

1.39 

.987 

Soya  bean  oil,  20%  }  
Linseed  oil,  60%      j. 

.289 

.857 

1.125 

Soya  bean  oil,  40%  f  ' 
Linseed  oil,  40%      ) 

.355 

1  05 

1.39 

Soya  bean  oil,  60%  f  ' 
Linseed  oil,  20%.  .  1 

.260 

.789 

1.03 

Soya  bean  oil,  80%  f  ' 
China  wood  oil  treated,  100%    
Linseed  oil,  80%                         } 

.130 

.182 

.297 
.559 

.375 

.728 

China  wood  oil  treated,  20%  (  
Linseed  oil,  60%                         \ 
China  wood  oil  treated,  40%   f  
Linseed  oil,  40%                        ) 
China  wood  oil  treated,  60%   f  
Linseed  oil,  20%                         ) 
China  wood  oil  treated,  80%  ]  
Kauri  gum,  33%  ) 
Linseed  oil,  33%  > 

.173 
.119 
.127 

061 

.540 
.348 
.375 

191 

.708 
.450 
.494 

.302 

Turpentine,  33%  ) 
Kauri  gum,  25%  ) 
Linseed  oil,  50%  ?    
Turpentine,  25%  ) 
Kauri  gum,  20%  ) 
Linseed  oil,  60%  / 

.096 
122 

.266 
367 

.346 
.449 

Turpentine,  20%  ; 
Kauri  gum,  15%  ) 
Linseed  oil,  70%  >  

187 

421 

.601 

Turpentine,  15%  ) 
Congo  copal  gum,  20%  ) 
Linseed  oil,  50%              >  

.228 

Turpentine,  30%             ) 
Sierra  Leone  copal,  20%  j 
Linseed  oil,  50%              >  

.099 

Turpentine,  30%             ) 
Zanzibar  gum,  20%  ) 
Linseed  oil,  50%        > 

082 

Turpentine,  30%       ) 
Amimi  gum,  20%  ) 
Linseed  oil,  50%    >  
Turpentine,  30%    ) 
Boiled  linseed  oil  (linoleate  type)  
Collodion  solution  (6  oz.),  80%  .1 
Boiled  linseed  oil,  20%                  )  

.080 

.210 
.201 

— 

— 

PHYSICAL  LABORATORY  PAINT   TESTS  85 


Microscopic  view  of  section  of  cedar        Microscopic  view  of  section  of  iraple 


Microscopic  view  of   section   of  white 
pine 


Gardner  photomicroscope  in  position 
against  painted  surface 


86 


PAINT   TECHNOLOGY  AND   TESTS 


Use  of  the  Microscope.  4.  The  microscope  is  a  necessary 
adjunct  of  every  well-ordered  paint  laboratory,  as  has  been 
recognized  throughout  the  whole  paint  industry.  The  writer 
has  attempted  to  collect  certain  data  which  may  materially 
assist  those  manufacturers  who  employ  this  instrument  to 
judge  of  the  quality  of  their  raw  and  finished  products.  The 
fineness  of  grinding  considerably  affects  the  quality  of  the  paint, 
and  this  can  be  easily  controlled  through  the  intelligent  use  of 
the  microscope.  This  instrument  may  also  be  used  to  detect 
certain  adulterations.  Appended  is  a  'table  giving  the  fineness 


Inside  White  on  White  Pine 

of  grinding  of  the  various  pigments,  together  with  their  char- 
acteristics under  the  microscope.  In  this  table  measurements 
are  given  both  in  millimeters  and  in  inches,  in  order  to  accom- 
modate itself  to  the  use  of  those  chemists  employing  a  millimeter 
stage  micrometer,  or  those  employing  the  English  or  inch  system. 
Although  it  is  not  yet  certain  that  any  and  all  combinations 
of  pigments  may  be  detected  under  the  microscope  the  writer 
is  working  toward  a  method  which  will  allow  a  manipulator  to 
judge  of  the  composition  of  the  paint  under  observation. 

In  order  to  properly  prepare  a  paint  for  microscopic  examina- 
tion, the  following  method  is  recommended:  A  microscopic  turn- 


PHYSICAL  LABORATORY  PAINT  TESTS 


87 


table  is  a  convenient  accessory  of  the  microscope,  and  its  use  is 
to  be  recommended.  A  glass  slide  being  placed  in  position  upon 
the  turn-table,  a  very  small  amount  of  either  the  pigment  rubbed 
up  in  oil,  or  the  paint,  is  applied  to  the  slide;  a  small  drop  of 
Canada  balsam  is  then  applied  by  means  of  a  glass  rod  dipped 
in  a  solution  of  balsam  in  xylol,  and  dropped  upon  the  slide. 
The  rod  is  then  used  to  thoroughly  incorporate  the  pigment  with 
the  balsam,  and  a  cleaned  cover  glass  is  dropped  over  the  whole 
and  pressed  down  tightly,  so  that  a  small  amount  of  balsam  will 
exude  from  under  the  edges  and  thus  firmly  seal  the  glass.  In 
order  to  make  permanent  slides  it  has  been  found  advisable  to 
rim  the  cover  glass  with  balsam  and  even  follow  this  up  with 
some  suitable  black  varnish,  the  slide  being  then  carefully  labeled 
and  placed  in  the  collection.  Following  is  a  table  of  the  charac- 
teristics of  the  fourteen  chief  pigments: 

TABLE  OF  THE  SIZE  OF  PARTICLES  OF  THE  CHIEF  PIGMENTS  WITH  THEIR 
CHARACTERISTICS  UNDER  THE  MICROSCOPE 


No. 

Name 

Diameter  in  Millimeters 

Diameter  in  Inches 

Small 

Aver. 

Large 

Small 

Aver. 

Large 

1 
2 
3 
4 
5 
6 

8 
9 
10 
11 
12 
13 
14 

Asbestine  
China  clay  . 

.002 

.003 
.00076— 
.00073 
.0037 
.0037 
.0015 
.0015 
.00037 
.00037 
.00076 

.0055 
.0037 
.0092 
.011 
.0050 
.0092 
.0018 
.0018 
.0018 
.0018 
.0030 
.0018 

.12 
.065 

.0172 
.0073 
.03 
.05 
.04 
.05 
.0037 
.0037 

.00037 
.0048 
.0066 

.00015 
.00009 
.00003 
.00003 
.00014 
.00014 
.00006 
.00006 
.000014 
.000014 
.00003 
.00002 
.00002 
.00002 

.00024 
.00014 
.00036 
.00044 
.00022 
.00036 
.00007 
.00007 
.00007 
.00007 
.00012 
.00007 

.049 
.025 
.0011 
.0003 
.0012 
.0022 
.0018 
.0021 
.00014 
.00014 

.00014 
.00018 
.00026 

Barium  carbonate  .  .  . 
Blanc  fixe  
Silex...  
Gypsum  
Amer.-Paris  white  .  .  . 
Barytes  
Zinc  lead  
Sublimed  white  lead  .  . 
Lithopone  

Zinc  oxide  
Quick  Pro.  lead  
Dutch  Pro.  lead  

.00046 
.00081 
.00081 

Film  Sectioning  and  Deductions  to  be  Drawn  Therefrom.     5. 

Investigations  were  undertaken  into  the  innermost  structure 
of  paint  films  as  revealed  under  the  microscope.  Up  to  the 
present  time,  work  has  been  done  upon  barytes,  asbestine,  blanc 
fixe,  and  white  lead,  painted  upon  wood,  and  a  combination 
paint  upon  wood.  The  films,  the  preparation  of  which  has 
been  described  in  the  foregoing,  were  sectioned  and  prepared 
for  microscopic  examination  in  the  following  manner: 


88 


PAINT  TECHNOLOGY  AND   TESTS 


A  solidifying  dish  was  partly  filled  with  low  melting-point 
paraffin  which  was  allowed  to  harden,  when  a  small  piece  of 
paint  was  thrown  upon  it  and  then  more  paraffin  poured  over  it. 
After  hardening,  sections  were  obtained  of  the  paint  film  by 
means  of  a  microtome. 

A  view  of  these  sections  of  paint  films  under  the  microscope 
gave  to  the  operator  a  better  idea  of  the  structure  of  a  paint 
than  had  ever  been  afforded  heretofore.  It  was  easy  to  per- 
ceive the  relative  position  of  the  pigment  particles  and  the 


Section  Barytes  Film 

three  coats.  The  penetration  of  one  coat  into  another  was 
easily  discernible,  and  measurements  were  made  upon  the  sec- 
tions in  order  to  determine  the  average  thickness  of  coat  and 
its  general  appearance. 

Sections  were  also  made  of  Inside  and  Outside  White  upon 
wood.  These  sections  revealed  under  the  microscope  the  thick- 
ness of  the  coats  and  also  the  penetration  of  the  priming  coat 
into  the  wood.  Appended  is  a  table  giving  microscopic  measure- 
ments. 


PHYSICAL  LABORATORY  PAINT  TESTS  89 

PAINT  SECTION  MEASUREMENTS  UNDER  MICROSCOPE 


Millimeters 

Inches 

Barytes 

3  coats  (sum)    

.1068 

.00421 

Single  coat    

.0356 

.00140 

Inside      TVhite  on  wood 

3  coats  (sum) 

.1624 

.00639 

Outside  coat 

.0230 

.00091 

Next  coat    

.0443 

.00175 

Field  in  photographs    

Next  coat    
Penetration  

.0620 
.0294 

.00245 
.00116 

White  lead                       

Inside  

.0215 

.00085 

Middle 

0405 

.00159 

Outside 

.0184 

.00073 

Asbestine 

3  coats  (sum)    
3  coats  (sum)    

.0811 
.1840 

.00319 
.00725 

Blanc  fixe 

3  coats  (sum)    

.1068 

.0042 

Outside      White  on  wood 

Single  coat    
Outside  coat 

.0356 
1329 

.00014 
.00523 

Inside 

1845 

.00727 

Penetration 

.0737 

.00290 

Polar  Micro-Examinations  and  Photomicrographs.  By  Polar 
Micro-Examination  is  meant  the  examination  of  pigments  under 
polarized  light.  A  polarizing  apparatus,  though  not  an  essential 
in  the  hands  of  the  paint  chemist,  is  nevertheless  much  to  be 
desired,  for  by  its  help  deductions  may  be  drawn  as  to  the  con- 
tents of  a  paint,  which  by  other  means  might  not  be  possible. 
The  polarizing  apparatus  as  marketed  by  most  manufacturers 
of  the  microscope  is  attached  in  the  following  manner: 

The  diaphragm  immediately  under  the  sub-stage  container 
is  swung  out  and  opened  to  its  widest  limit,  allowing  the  insertion 
of  the  polarizer.  This  polarizer  carries  one  of  the  pair  of  Nicols 
prisms  and  is  countersunk  to  allow  of  the  introduction  of  gypsum 
or  selenite  plates.  The  analyzer  fits  over  the  eyepiece  on  the 
tube. 

The  use  of  polarized  light  upon  paint  is  valuable  on  account  of 
its  action  upon  crystalline  substances.  The  re-enforcing  pig- 
ments, such  as  Asbestine,  China  Clay,  Gypsum,  Silex,  Barytes, 
etc.,  are  crystalline  and  consequently  act  upon  the  polarized 
light.  In  most  cases  these  pigments  are  used  in  ready-mixed 
paints  in  small  amounts,  varying  between  5  and  25%.  When 
a  slide  containing  a  small  amount  —  for  example,  less  than 


90  PAINT  TECHNOLOGY  AND   TESTS 

3%  —  of  these  crystalline  pigments  is  examined  under  the 
microscope  by  ordinary  transmitted  light,  they  will  often 
escape  observation,  owing  to  the  small  amount  in  which  they 
are  present.  However,  in  the  case  of  polarized  light,  this  could 
hardly  happen. 

A  slide  of  paint  containing  these  re-enforcing  pigments  is 
prepared  in  the  usual  manner.  On  examining  this  under  the 
microscope  and  using  the  polarizing  apparatus,  the  crystalline 
pigments  are  at  once  detected  by  revolving  the  analyzer.  At 
one  position  of  the  analyzer,  one  sees  an  ordinary  field,  as  with 
transmitted  light,  but  if  one  revolves  the  analyzer,  the  field 
gradually  becomes  darker  until  total  darkness  is  obtained 


Microscopic  View  of  Barytes  under 
Polarized  Light 

throughout,  except  in  such  places  where  crystalline  substances 
are  present,  when  the  crystal  is  shown  up  with  beautiful  dis- 
tinctness. Photomicrographs  of  various  single  pigments  and 
pigment  combinations  are  shown  under  Chapter  III. 

Effect  of  Pigments  on  Oil.  Certain  pigments  have  the  prop- 
erty of  acting  upon  the  linseed  oil  in  which  they  are  ground, 
forming  metallic  linoleates  which  accelerate  the  drying  of  oil. 
This  is  especially  true  of  lead  and  zinc  pigments.  The  inert 
crystalline  pigments,  when  ground  in  linseed  oil  and  painted 
out,  distribute  the  oil  so  as  to  allow  a  great  surface  to  be  exposed 
to  the  air.  Thus  by  physical  action,  and  possibly  catalytic  or 
contact  action,  these  inert  pigments  stimulate  the  drying  of  oil 


PHYSICAL  LABORATORY  PAINT   TESTS 


91 


paints  in  which  they  are  ground.  Lead  and  zinc  paints,  of 
course,  have  the  greatest  drying  values  on  account  of  the  added 
effect  of  the  linoleates  formed,  as  outlined  above.  The  writer 
has  made  a  series  of  tests  in  which  the  action  of  various  pigments 
upon  linseed  oil  is  shown.  The  tests  were  made  in  the  following 
manner: 

Five  grams  of  each  of  a  series  of  commonly  used  paint  pigments, 
including  those  of  inert  crystalline  nature  as  well  as  the  more 
valuable  amorphous  pigments  which  are  considered  more  or 
less  chemically  active,  were  ground  separately  in  an  agate 
mortar,  with  5  grams  of  raw  linseed  oil.  The  ground  paste 
in  each  case  was  placed  in  a  marked  glass  beaker,  and  allowed 
to  stand  in  a  dustless  section  of  the  laboratory  for  one  month. 
The  oil-pigment  paste  from  each  beaker  was  then  separately 
extracted  with  benzine  to  remove  the  linseed  oil  from  the  pig- 
ment. The  benzine  solutions  of  oil  were  then  heated  to  remove 
the  benzine  and  the  residue  of  oil  burned  to  ash  in  crucibles. 
The  ash  from  each  test  was  weighed,  and  if  it  ran  above  the 
percentage  of  ash  determined  on  a  blank  sample  of  linseed  oil 
(namely,  .003%),  the  ash  was  analyzed  qualitatively  for  metallic 
constituents.  The  following  table  of  results  shows  the  per- 
centage increase  in  ash,  as  well  as  the  constituents  of  ash  on  the 
various  samples  tested: 

TABLE  OF  RESULTS 


Pigment  in  Oil 

Per.  cent  of 
Ash  in  Oil 
Extracted 
from  Oil-Pig- 
ment Paste 

Analysis  of  Ash 

Raw  linseed  oil  without  pigment  
Barytes                        

0.003 
0.003 

— 

Blanc  fixe                  

0.003 



Silica                      

0.003 



Asbestine               

0.005 



China  clay  .          

0.007 



\Vhitinff 

0.008 



Chrome  vellow 

0.025 

Lead  oxide  (PbO) 

Lithopone                      •                            •  • 

0.031 

Zinc  oxide  (ZnO) 

Prussian  blue                ....              

0.032 

Iron  oxide  (Fe2O3) 

Sublimed  white  lead    
Zinc  oxide 

0.033 
0.105 

Lead  oxide  (PbO) 
Zinc  oxide  (ZnO) 

Corroded  white  lead 

0.116 

Lead  oxide  (PbO) 

Red  lead                       '                   

0.2112 

Lead  oxide  (PbO) 

92  PAINT   TECHNOLOGY  AND   TESTS 

Observation  of  these  results  shows  that  pigments  such  as 
Barytes,  Blanc  Fixe,  and  Silica  have  no  chemical  action  on  the 
linseed  oil.  The  results  on  Asbestine  and  China  Clay  also  are 
negative,  the  extremely  slight  increase  in  amount  of  ash  from 
these  samples  probably  being  due  to  traces  carried  over  mechani- 
cally into  the  oil  mixture;  the  last  named  pigments  being  more 
fluffy  and  difficult  to  separate  from  oil.  Slight  action  seemed  to 
be  apparent  in  the  case  of  whiting,  a  pigment  somewhat  alkaline 
in  nature.  A  longer  test  might  have  shown  this  pigment  to  have 
possessed  still  greater  action.  Corroded  white  lead  showed 
considerable  action,  resulting  in  the  formation  of  lead  linoleate 
or  some  other  organic  compound.  Zinc  oxide  and  lithopone, 
the  latter  pigment  containing  30%  of  zinc  sulphide,  both 
indicated  action  on  the  oil.  Chrome  yellow  (chromate  of  lead) 
showed  some  action,  as  did  also  Prussian  blue,  the  ash  from 
the  last  named  pigment  showing  a  heavy  percentage  of  iron 
oxide. 

Red  Lead  showed  a  most  astounding  gain  in  these  tests, 
chemical  action  of  the  pigment  on  the  oil  being  apparent  soon 
after  the  tests  were  started,  as  shown  by  the  formation  of  a 
hard  cake  with  the  linseed  oil. 

The  Raw  Linseed  Oil  which  was  used  in  these  tests  had  an 
acid  value  of  1.84%,  which  is  very  low.  The  neutralization  of 
this  free  fatty  acid  by  some  of  the  alkaline  pigments  used,  may 
account  for  part  of  the  increased  percentage  of  ash,  but  in  most 
cases  the  pigments,  and  more  especially  the  basic  pigments, 
had  a  direct  saponifying  action  upon  the  glycerides  of  the  oil. 


CHAPTER   V 
THE  THEORY  AND   PRACTICE  OF   SCIENTIFIC  PAINT  MAKING 

Laws  of  Paint  Making.  To  secure  a  proper  comprehension 
of  the  composition  of  paints,  and  to  be  able  to  interpret  the 
functions  of  their  various  constituents,  requires  an  understand- 
ing of  the  general  physical  principles  involved.  The  modern 
grinder  has  accepted  the  Law  of  Minimum  Voids,  and  upon  this 
law  he  bases  the  design  of  paint  formulae,  aiming  toward  the 
production  of  what  have  been  properly  termed  Scientifically 
Prepared  Paints.  Perry's  formulation  of  the  Law  of  Minimum 
Voids  in  a  paint  coating,  and  the  analogy  which  he  has  drawn 
between  a  scientifically  prepared  paint  and  a  well-proportioned 
concrete,  was  the  result  of  genuine  scientific  thought  following 
observation  and  experimentation.  It  must  be  admitted  that 
analogies  are  not  always  safe  to  draw  conclusions  from,  but  it 
surely  is  no  fallacy  in  reasoning  to  draw  analogies  between  these 
two  materials,  when  they  resemble  each  other  in  so  many  ways. 
To  carry  out  processes  of  reasoning,  and  to  formulate  laws  from 
such  close  analogies,  is  certainly  a  step  in  the  right  direction. 

A  graphic  summary  of  the  analogies  between  a  properly  pro- 
portioned concrete  and  a  paint,  are  shown  on  next  page. 

Although  this  table  graphically  summarizes  the  principles 
involved,  the  matter  is  presented  with  greater  clearness  in 
the  following: 

Law  No.  1  —  The  law  of  minimum  voids  to  be  observed  in 
constructing  a  paint  formula  —  this  law  having  already  been 
accepted  as  mathematically  correct  and  technically  proved  in 
the  technology  of  concrete  and  cement. 

Corollary  —  The  requisite  thickness  of  a  paint  film  together 
with  the  utmost  attainable  strength  and  impermeability  can 
best  be  obtained  by  a  properly  proportioned  blend  of  pigments 
of  three  or  more  determinate  sizes. 

Law  No.  2  —  The  law  of  the  flat  arch  in  paint  coatings  —  i.e., 
the  fact  that  in  studying  the  fundamental  physical  principles 

93 


94 


PAINT   TECHNOLOGY  AND   TESTS 


AN    EXHIBITION    OF    CERTAIN    ANALOGIES    GOVERNING    THE    MANUFAC- 
TURE   OF   CONCRETE   AND    OF   PAINT 


1  Concrete  aggregate  =  solids  +  vehicle 

2  Solids  =  coarse  +  medium  +  fine 

(stone)        (gravel)       (sand) 


3  Vehicle  = 

=  reactive  binder  +  evapor'g  thinner 
(  cement  and  com-  )     (excess  water) 
( bining  water          J 

4  Solids  +  compacting  = 

(tamping) 

=  elimination  of  accidental  voids  + 
+  proper  adhesive  contact 

5  Vehicle  +  reaction  =  hydrosilicates,  etc. 

(setting) 

6  Solids  +  vehicle  + 

+  lubrication  +  chemical  reaction  =  ) 
=  final  product   (  solidified  binder  +  J 
\  +  solids) 

7  Final  product  =  concrete 

[  shearing  ] 

(of  max.  strength     j  tensile 

[  crushing,  etc.      J 


Paint  aggregate  =  solids  +  vehicle 
Solids  =  coarse  +  medium  -+-  fine 

f  pulverized  }    (  precip-  )  ,(        x 
(pigments    cryst'lline  \  { itated    }  (fume) 

(etc.) 
Vehicle  = 

=  reactive  binder  +  evaporating  thinner 
(linseed  oil)  (volatiles) 

Solids  +  compacting  = 

(brushing) 

=  elimination  of  accidental  voids  + 
+  proper  adhesive  contact 
Vehicle  +  reaction  =  Jinoxyn 

(drying) 
Solids  +  vehicle  + 

+  lubrication  +  chemical  reaction  = 
=  final  product    (  solidified  binder  +  ) 
I       +  solids  J 

Final  product  =  paint  coating 

[  strength  ] 

(of  maximum  \  impermeability       [• 

1,  durability  J 


If  we  assume  for  both  paint  and  concrete 

proper  lubrication 

proper  proportion  of  vehicle  and  solids 
Then  the  essential  difference  between  a  thin  film  of 


Concrete 


Cement  Binder 


and 

is 


Paint 


Linoxyn  Binder 


Disadvantages 


Non-elastic  and  hence  an  impracticable 
binder  for  a  film  to  protect  non-similar  struc- 
tural surfaces. 


Slowly   perishable  from  oxidation  by  the 
air. 


Advantages 
Durable  and   with   the   qualities   of   a 


natural  mineral. 


Semi-elastic  and  therefore  a  practi- 
cable binder  for  a  film  to  protect  struc- 
tural surfaces. 


Postulate   (def.   Webster's  Dictionary  —  A  self-evident  problem) 

Postulate  No.  1  —  The  organic  linoxyn  or  semi-elastic  binder  of  the  paint  vehicle  (unlike  the 
cement  binder)  is  perishable  and  its  purity,  strength  and  protection 
from  attack  means  life  to  the  paint  coating,  and  hence  the  life  of  the 
oil  is  the  life  of  the  paint. 

Postulate  No.  2  —  The  inorganic  or  oowdered  mineral  solids  of  a  paint  coating  will  crumble 
unless  held  together  by  the  binder,  but  the  imperishable  pigments  must 
be  so  ground  and  blended  in  the  binder  that  they  will  protect  the  binder 
and  present  the  greatest  possible  solid  front  to  the  atmospheric  attack. 


Pattire  ^  great6St  protection  and  life  for  the  ^oxyn,  together  with  the  durable 

Therefore 
Should  expose  to  air  decay 


within  limits  of  physical  strength 

The  greatest   amount   of   pigm't   material 

(which  is) 

Durable    and    with   the   inert   qualities   of 
natural  mineral 


within  limits  required  for  elasticity,  etc. 
The  least  amount  of  exposed  linoxyn 

or 

Considering  the  linoxyn  present  between 
pigment  particles  as  the  void  or  point  of 
attack, 

Then 

the  minimum  exposure  of  linoxyn 
or  minimum  voids  obtainable  by  proportioned  pigments  of  different  particle  sizes. 


THEORY  AND  PRACTICE  OF  PAINT  MAKING  95 

governing  the  strength  and  durability  of  a  paint  coating  it  is 
necessary  to  regard  the  coating  as  consisting  of  a  series  of  flat 
arches,  in  which  the  pigment  particles  of  largest  characteristic 
size  serve  as  the  piers  or  supports  for  the  flat  arches  of  which  the 
continuous  film  is  composed. 

Corollary  A  —  The  strength  and  durability  of  a  paint  coating 
is  determined  by  the  strength  and  durability  of  the  piers  or 
supports  (which  consist  of  the  characteristic  pigment  particles 
of  the  largest  size). 

Corollary  B  —  Owing  to  their  inherent  strength  and  durability 
the  pigment  particles  of  largest  characteristic  size  which  serve 
as  supports  for  the  paint  coating  should  consist,  in  part  at  least, 
of  chemically  inert  pigments,  such  as  natural  crystalline  barium 
sulphate,  calcium  carbonate,  magnesium  silicate,  etc. 

Corollary  C  -  -  It  follows  directly  that  the  thickness  of  a  paint 
coating  is  determined  by  the  particles  of  pigments  having  the 
largest  characteristic  size,  even  if  that  pigment  be  present  only 
in  moderate  percentage.  Upon  this  principle  depends  the  com- 
paratively great  thickness  of  film  and  moderate  spreading  rate 
of  paints  composed  of  such  pigments  as  basic  carbonate  —  white 
lead,  red  lead,  barytes,  etc.,  and  the  strongly  contrasted  thin- 
ness of  film  and  high  spreading  rate  of  paints  composed  of  the 
sublimated  pigments  such  as  lamp  black,  zinc  oxide,  basic  sul- 
phate —  white  lead,  zinc-lead  white,  leaded  zinc,  etc. 

In  commenting  upon  the  announced  laws  set  forth  above, 
Heckel  says:  "  The  recognition  of  these  laws  was  an  exercise 
of  pure  deduction.  Paint  manufacturers  before  Mr.  Perry's 
announcement  were  producing  paints  containing  three  or  more 
pigments  with  particles  of  varying  characteristic  sizes;  but  their 
procedure  was  based  largely  on  empirical  knowledge,  the  result 
of  accumulated  experience,  due  to  a  conscientious  endeavor  to 
produce  the  highest  type  of  paints  for  economic  service.  In 
the  absence  of  any  law  to  govern  or  to  limit  the  use  of  the  rein- 
forcing pigments,  inexperienced  manufacturers  had  brought 
upon  the  market  paints  which  were  badly  proportioned  as  to 
the  several  pigments,  or  burdened  beyond  the  limits  of  effective- 
ness with  reinforcing  pigments.  To  all  paint  manufacturers 
Perry  rendered  a  substantial  service  in  deducing  for  them  the 
laws  set  forth  in  his  address.  In  the  results  following  a  recogni- 
tion of  these  laws  there  was  nothing  new  or  startling,  but  Perry 


96 


PAINT   TECHNOLOGY  AND   TESTS 


Series  of  Paint  Chasers,  Mixers,  and  Grinders 

was  the  first  to  give  the  principles  from  which  it  can  be  deter- 
mined in  advance  whether  a  paint  formula  will  prove  to  be  physi- 
cally good  or  bad  in  practice. 

"  As  has  been  before  stated,  he  was  not  the  first  to  recognize 
the  law  governing  minimum  voids,  but  by  that  scientific  use  of 
the  imagination  which  Tyndall  so  highly  commends,  he  recog- 
nized, as  by  inspiration,  the  fundamental  similarity  existing 


Overhead  Churn  Mixer 


Battery    of    Paint    Mixers    and    Grinders    of 
Modern  Underdriven  Type 


Photographs  courtesy  of  Ernest  Heath 

View  showing  Shrinkage  in  Bulk  of  Paint  Pigment  after  being 
ground  in  Oil.  Filled  Barrel  on  Right  with  the  Oil  forms  one- 
third  Barrel  Paste  as  shown  in  Barrel  on  Left  97 


98  PAINT  TECHNOLOGY  AND   TESTS 

between  a  film  composed  of  solid  particles  cemented  together 
by  a  semi-solid  homogeneous  menstruum  and  a  layer  of  concrete 
composed  of  solid  particles  cemented  together  by  a  solid  homo- 
geneous medium.  His  application  of  the  law  permits  the  paint 
manufacturers  to  design  a  paint  formula  with  full  knowledge  of 
the  controlling  conditions,  so  that  it  shall  produce  a  coating 
neither  too  thick,  and  therefore  uneconomical  and  subject  to 
excessive  internal  strains,  nor  too  thin,  and  thus  weak  and  in- 
efficient for  protection.  That  Mr.  Perry's  contention  was 


J 


View  showing  careful  Dressing  of  Bull  Stone  Mill  from 
Grinder 

well-founded,  other  paint  technologists  have  since  demonstrated; 
notably  Mr.  Wirt  Tassin,  in  his  microscopic  studies  of  paint 
films  in  situ,  and  Prof.  G.  W.  Thompson  who,  in  his  address  to 
the  Penna.  Association  of  Master  Painters  at  Reading,  said :  — 
I  want  to  agree  with  Mr.  Perry  *  *  *  where  he  says  that  a 
pigment  should  be  made  up  of  particles  of  different  sizes.  Mr. 
Perry  also  draws  a  further  parallel  between  paint  and  concrete 
where  he  refers  to  the  form  of  the  reinforcing  pigment  particles 
and  suggests  that  in  paint  coatings  as  in  concrete  a  field  can  be 


THEORY  AND  PRACTICE  OF  PAINT  MAKING  99 

found  for  the  chemically  inert  pigments  with  rod-like  or  hair- 
like  structure,  to  strengthen  the  film,  just  as  the  steel  rods  and 
iron  mesh  are  used  to  reinforce  concrete  in  structural  work  - 
a  suggestion  which,  since  the  first  publication  of  the  address,  has 
been  widely  accepted  as  a  practical  aid  in  the  manufacture  of 
good  paints." 

Use  of  Inert  Pigments.  There  seems  to  be  no  reasonable 
doubt  as  to  the  efficiency  of  a  small  amount  of  inert  pigments 
in  paint,  and  the  writer  has  often  compared  the  manufacture  of 
paint  of  the  above  type  to  the  making  of  various  alloys  wherein 
zinc,  copper,  and  other  metals  are  added  to  gold  in  order  to  make 
a  product  possessed  of  greater  durability,  etc. 


Batteries  of  Color  Grinding  Mills 

There  has  been  considerable  inquiry  as  to  just  what  is  meant 
by  the  statement  that  "  a  moderate  percentage  of  inert  pig- 
ments, combined  with  properly  adjusted  mixtures  of  white  lead 
and  zinc  oxide,  have  given  wonderful  service  in  all  the  tests." 
The  writer  has  been  asked  to  define  what  "  moderate  "  means. 
A  "  moderate  percentage  of  inert  pigments  "  should  be  defined 
as  that  amount  of  natural  crystalline  pigments  that  will,  when 
mixed  with  white  lead  and  zinc  oxide,  not  materially  detract 
from  the  hiding  power  of  white  lead  and  zinc  oxide.  It  is  possi- 
ble to  mix  a  certain  percentage  of  these  crystalline  pigments 
with  white  lead  and  zinc  oxide,  and,  by  thorough  grinding,  incor- 
porate them  in  such  a  manner  that  the  mixture  will  show  nearly 
as  good  a  hiding  power  as  the  straight  white  lead  and  zinc  oxide. 


100  PAINT   TECHNOLOGY  AND   TESTS 

When  certain  limits  have  been  reached,  however,  and  these 
limits  must  be  determined  by  the  manufacturer  and  painter  in 
making  practical  tests,  the  further  addition  of  inert  pigments 
lowers  the  hiding  power  of  the  paint  and  therefore  lowers  the 
value  of  the  paint.  These  remarks  do  not  apply  to  artificial 
crystalline  pigments,  such  as  precipitated  whiting,  which  possess 
greater  hiding  values  than  the  natural  pigments. 

Perry's  Principles  of  Paint  Making.  Parts  of  the  original 
paper  l  in  which  Perry  so  clearly  set  forth  the  principles  from 
which  the  preceding  laws  were  formed,  follow: 

Sealing  Quality  or  Imperviousness  of  the  Coating.  "  It  has 
been  emphasized  that  for  durability  and  protection,  the  strength 
and  imperviousness  of  a  paint  coating  are  vital  factors.  The 
protective  value  of  the  paint  coating  of  course  ceases  with  its 
chalking  or  disintegration,  but,  while  it  is  true  that  the  protecting 
or  final  life  of  the  coating  ceases  with  this  disintegration,  it  is 
also  true  that  a  paint  coating  has  always  during  its  true  life  more 
or  less  porosity  from  the  nature  of  the  linoxin  or  oxidized  linseed 
oil.  Therefore  during  its  protecting  life  the  degree  of  its  imper- 
viousness influences  its  resistance  to  attack  upon  its  own  life  and 
its  protection  of  the  underlying  materials.  The  more  impervious 
the  paint  coating  without  loss  of  strength,  the  slower  the  oxida- 
tion or  disintegration  of  the  paint  coating  itself  and  the  greater 
protection  to  the  underlying  material. 

"  A  coating  of  linseed  oil  alone  is  not  only  weak,  but  the 
simplest  and  crudest  experiments  will  show  its  porosity  and  this 
porosity  increases  rapidly  with  progressive  oxidation,  the  porosity 
of  course  definitely  hastening  the  over-oxidation  or  chalking. 
In  proportion,  therefore,  to  our  success  in  filling  the  voids  in  the 
linseed  oil  film  with  proper  pigment  materials,  we  will  in  that 
degree  succeed  in  excluding  agencies  of  decay,  not  only  from  the 
mass  of  the  paint  coating  itself,  but  also  from  the  surface  to  be 
protected.  These  conditions  are  exactly  parallel  in  the  require- 
ments and  performance  of  the  best-made  concrete,  and  Taylor 
&  Thompson  in  their  work  on  concrete  have  clearly  stated  that 
to  obtain  imperviousness  there  must  be  freedom  from  voids,  and 
that  to  obtain  these  conditions,  the  materials  used  must  have 
at  least  three  determining  sizes. 

1  Physical  Characteristics  of  a  Paint  Coating.  R.  S.  Perry.  Michigan 
Chapter,  Amer.  Institute  of  Architects,  1907. 


Equal  Volume  (One  Cubic  Centimetre)  of  Each 
Size  of  Shot  Taken.  Note  that  the  Smaller 
Shot  Cover  more  than  Half  as  much  again  as 
the  Larger  Shot  and  the  Voids  are  Smaller. 


Diagram  Illustrating  Two  Determining  Sizes  of 
Solid  Particles  in  Concrete 


Diagram  Illustrating  Three  Determining  Sizes  of 
Solid  Particles  in  Concrete 


102  "PAINT  TECHNOLOGY  AND  TESTS 

1  It  is  a  fact  that  with  particles  of  different  sizes  as  against 
uniform  size  the  densest  mixture  can  be  obtained.  This  is  so 
evident  as  to  require  no  proof.'  It  follows  that  the  least  density 
and  hence  the  largest  percentage  of  voids  occur  when  the  grains 
are  all  of  the  same  size,  and  it  is  shown  that  the  most  voids  occur 
in  a  mass  of  large  particles.  The  least  voids  occur  when  the 
voids  between  the  large  particles  are  filled  with  smaller  particles 
and  when  these  smaller  voids  between  the  smaller  particles  are 
in  turn  filled  with  still  finer  particles.  In  other  words  —  particles 
with  three  determining  sizes  will  fill  up  a  given  space  more  com- 
pletely than  particles  of  two  determining  sizes  and  very  much 
more  completely  than  particles  of  one  size. 

Elasticity  and  Strength.  "  The  paint  coating  here  again  is 
governed  by  many  of  the  laws  which  govern  the  similar  material, 
i.e.,  concrete.  We  find,  by  again  referring  to  Taylor  &  Thompson, 
on  Concrete,  page  275,  that  tests  at  the  Watertown  Arsenal  on 
concrete  convinced  the  investigators  that  the  ultimate  strength 
of  a  concrete  is  identical  with  the  shearing  strength  of  particles 
of  stone  making  up  the  aggregate. 

'''  This  means  that  in  its  ultimate  form  the  good  concrete  will 
crack  or  shear  through  the  broken  rock  contained  therein,  and 
resistance  to  shearing  is  directly  proportionate  to  the  strength  of 
the  broken  rock  chosen  for  the  mixture.  The  film  of  semi-liquid 
linseed  oil  when  fresh  is  extremely  weak,  but  as  it  hardens,  its 
characteristics  and  physical  properties  will  obviously  be  those 
qualities  which  are  a  composite  of  the  qualities  of  the  solid  par- 
ticles and  of  the  semi-solid  linolein  incorporated  together  in  the 
paint  coating.  These  physical  properties  of  the  suspended  and 
incorporated  pigments  profoundly  modify  the  film  in  this  respect. 

"  The  dried  vehicle,  linoxin,  is  notable  for  its  elasticity,  and 
it  is  weak  in  crushing  and  tensile  strength,  and  in  hardness  or 
resistance  to  surface  wear.  The  fact  that  it  is  a  semi-solid 
furnishes  an  opportunity  to  modify  and  improve  those  charac- 
teristics of  a  solid  in  which  it  is  deficient.  The  semi-solid,  rubber- 
~like  linoxin  between  the  coarser  particles  of  the  pigment  obviously 
uses  these  coarser  particles  as  supporting  points.  The  medium 
sized  particles  of  the  second  group  of  alteration  products  serve 
the  same  purpose  as  the  broken  rock  in  concrete.  The  coarser 
particles  absolutely  do  not,  and  can  not,  serve  the  purpose  of 
stiffening  or  of  reinforcing  or  modifying  the  consistency  and 


THEORY  AND  PRACTICE  OF  PAINT  MAKING          103 

qualities  of  the  semi-solid  linoxin,  for  a  number  of  reasons,  one 
of  which  may  be  mentioned,  namely,  that  particles  of  the  first, 
or  coarse,  class  have  a  determining  size  which  is  a  large  fraction 
—  a  heavy  percentage  —  of  the  total  thickness  of  coating,  and  are 
in  some  instances  thicker  in  diameter  than  the  thickness  of  an 
oil  coating  not  reinforced  with  the  fine  or  fire  group. 

"  We  must  think  of  the  coarser  particles  as  piers.  The  mix- 
ture of  linoxin  with  the  other  two  groups  of  particles  in  the  spaces 
between  these  coarser  particles,  or  piers,  is  the  true  paint  body 
and  consists  of  flat  reinforced  arches  which  have  the  extra  support 
of  falsework,  in  the  shape  of  the  structural  material  on  which 
the  coating  rests.  Asbestine  pulp,  a  natural  product  and  one 
of  our  most  important  natural  reinforcing  pigments,  serves  not 
only  in  the  coarse  group  as  supporting  particles  for  the  linoxin 
arch,  but  also  because  of  its  peculiar  properties  serves  the  more 
important  purposes  of  reinforcement.  It  retains,  no  matter 
how  finely  ground,  its  peculiar  needle-like,  or  rod-like,  form  of 
particles,  and  obviously  serves  the  purpose  of  reinforcing  the  flat 
arch  of  linoxin,  exactly  as  iron  bars  or  iron  netting  serve  in  rein- 
forced concrete  arches.  The  medium  sized  particles  of  the  second 
group  of  pigments  produced  by  chemical  alteration  or  precipi- 
tation, serve  the  purpose  of  the  broken  rock  in  concrete,  and 
together  with  the  coarser  supporting  particles  and  the  finest 
reinforcing  particles,  give  minimum  voids  and  a  maximum 
imperviousness  to  agencies  of  internal  decay. 

"  It  goes  without  saying  that  the  pigments  of  any  one  group 
contain  particles  of  dimensions  which  fall  into  the  other  two 
groups,  but  no  one  pigment  supplies  the  correct  proportion  of 
each  of  the  three  required  dimensions,  and  each  pigment  has  so 
large  a  percentage  of  approximate  dimensions  as  to  bar  it  from 
exclusive  use  in  the  other  two  groups.  Given  similar  homogene- 
ous coatings  under  identical  conditions,  we  recognize  the  law 
that  elasticity  will  vary  directly  with  thickness.  Direct  deduc- 
tion from  this  law  teaches  us  that  of  two  paint  coatings  equal 
in  wear,  in  strength,  opaqueness,  and  in  all  other  qualities  except 
thickness,  we  should  choose  the  thinner  coating.  Therefore  if  we 
have  two  paint  coatings  fulfilling  every  requirement,  the  first 
compounded  with  pigments  giving  a  thicker  coating  and  the 
second  with  pigments  yielding  a  thinner  coating,  we  must  choose 
the  second  formula  and  obtain  the  thinner  coating. 


104  PAINT   TECHNOLOGY  AND   TESTS 

Adhesive  Power.  "  The  adhesion  of  the  linoxin  to  the  coarse 
group  of  particles  and  to  the  underlying  material  is  vital  to  the 
life  of  the  paint  coating.  If  the  coating  parts  from  the  surface 
beneath,  we  have  scaling  or  peeling.  It  is  universally  admitted 
that  this  will  result  from  use  of  zinc  oxide  as  the  sole  pigment. 
We  have  only  to  conceive  of  our  flat  arch  of  reinforced  linoxin 
and  leave  out  our  points  of  support,  to  realize  that  this  is  the 
inevitable  result  if  the  coating  be  subject  to  extreme  exposure, 
although  good  results  may  be  obtained  from  zinc  oxide  used  alone, 
as,  for  instance,  in  interior  house  painting  where  extreme  changes 
of  temperature  and  exposure  are  avoided. 

"  Three  major  lines  of  force  hold  our  linoxin  in  place  —  adhesion 
toward  the  underneath  surface,  adhesion  to  the  coarse  particles, 
and  cohesion  within  the  linoxin  itself.  These  lines  must  be 
represented  by  a  flat  arch  of  linoxin  with  a  downward  pointing 
magnet  therefrom,  to  represent  adhesion  to  the  surface.  Mag- 
nets on  each  side  of  the  arch  pointing  toward  the  supporting 
coarse  particles,  and  two  magnets  within  the  arch  and  pointing 
toward  each  other,  or  to  the  centre  of  the  arch,  these  latter  to 
represent  the  force  of  cohesion." 


CHAPTER   VI 
THE  SCOPE  OF  PRACTICAL  PAINT  TESTS 

The  Pigment  Contention.  During  the  year  1906  officials  of 
the  North  Dakota  Agricultural  Experiment  Station  examined 
a  number  of  paints  on  sale  in  the  northwestern  States.  The 
presence  of  large  quantities  of  inert  pigments  as  well  as  water, 
in  some  of  these  paints,  prompted  agitation  for  State  laws 
requiring  the  formula-labeling  of  paints.  Certain  paints  made 
of  white  opaque  pigments  such  as  white  lead  and  zinc  oxide  were 
exempted  from  the  statute.  The  white  opaque  pigments  used 
in  these  paints  were  believed  by  certain  manufacturers  as  well 
as  by  many  prominent  paint  authorities  of  high  standing  to  be 
benefited  in  their  wearing  value  by  the  addition  of  small  per- 
centages of  inert  crystalline  pigments,  such  as  barytes,  silica, 
China  clay,  etc.  Laboratory  experiments  had  already  deter- 
mined that  these  inert  crystalline  pigments  had  a  certain  defi- 
nite action  in  increasing  the  life  of  paints,  but  it  had  become 
evident  that  they  should  be  used  with  discretion,  in  moderation, 
and  with  a  proper  understanding  of  their  limitations,  if  the 
best  results  were  to  be  obtained.  The  addition  of  very  large 
quantities  of  such  pigments  was  not  indulged  in  by  discriminat- 
ing manufacturers,  but  the  exact  percentage  to  use  was  a  matter 
of  great  doubt,  even  to  the  most  experienced.  In  order  to 
determine  just  what  percentage  of  crystalline  pigments,  admixed 
with  white  opaque  paint  pigments,  would  give  the  best  service 
and  results,  it  seemed  imperative  that  practical  paint  tests  should 
be  made.  A  series  of  paint  tests  on  commercial  brands  of  paint 
had  already  been  started  at  the  Fargo  Agricultural  College, 
and,  at  the  suggestion  of  the  Paint  Manufacturers'  Association 
of  the  United  States,  another  series  of  practical  paint  tests  were 
instituted,  and  carried  out  under  the  supervision  of  Dr.  E.  F. 
Ladd,  Director  of  the  North  Dakota  Experiment  Station. 

Test  Fences  to  Solve  the  Problem.  It  was  apparent  that 
the  pigment  question  could  be  solved  only  through  field  tests 

105 


106  PAINT  TECHNOLOGY  AND   TESTS 

made  on  a  comprehensive  basis  and  placed  under  the  control  of 
scientific  and  technical  societies  of  renown,  so  that  they  might 
be  fair  and  unbiased  from  every  standpoint.  In  order  to  secure 
a  comparison  of  the  wearing  of  different  paint  formulas  in  various 
sections  of  the  country  and  under  differing  climatic  conditions, 
another  series  of  tests  was  started  in  the  East  soon  after  the 
North  Dakota  tests  had  been  started.  Simultaneously  fences 
were  erected  at  Atlantic  City,  N.J.,  and  Pittsburg,  Pa.  The 
site  of  the  Atlantic  City  fence  is  a  strip  of  land  running  due 
north  from  Atlantic  and  Savannah  Avenues  and  within  a  short 
distance  from  the  Atlantic  Ocean,  the  exposure  being  a  severe 
one.  The  site  of  the  Pittsburg  fence  is  back  of  the  athletic  field 
of  the  Carnegie  Technical  Schools,  the  fence  running  east  and 
west  and  being  exposed  to  the  heavily  charged  sooty  atmosphere 
coming  from  the  many  industrial  plants  near  by. 

Construction  of  Framework  of  Fences.  At  these  two  loca- 
tions framework  fences  were  built,  upon  which  were  placed  a 
series  of  painted  panels.  Heavy  yellow  pine  posts  six  inches 
square  were  set  in  the  ground  about  six  feet  apart  and  to  the 
depth  of  about  four  feet,  upon  a  concrete  base.  The  posts  were 
solidly  tamped  and  then  braced  at  the  top  with  supplementary 
studding  braces  two  inches  thick.  Connecting  the  posts  was  a 
line  of  studding  six  inches  by  two  inches,  forming  a  solid  frame- 
work, the  bottom  of  which  was  approximately  fifteen  inches  from 
the  ground.  The  bottoms  and  tops  of  the  fences  were  protected 
by  heavy  boards  two  inches  thick,  so  that  the  moisture  and  rain 
might  be  prevented  from  working  itself  up  into  the  wood.  The 
whole  fence  was  sheathed  with  twelve-inch  planed  white  pine, 
thus  forming  a  solid  background  for  the  test  panels. 

Lumber  for  Panels.  The  lumber  for  the  test  panels  was 
most  carefully  selected,  being  of  three  grades  —  white  pine, 
yellow  pine,  and  cypress.  A  large  amount  of  each  grade  of 
lumber  was  secured,  and  after  the  best  portion  had  been  made 
up  into  panels,  the  panels  were  inspected  by  an  expert  lumber 
classer;  nearly  40%  being  rejected  on  account  of  the  presence 
of  knots  or  sappy  places  which  appeared  upon  the  surface. 
Each  of  the  panels  finally  passed  upon  as  suitable  for  the  test 
was  branded  with  a  hot  iron  with  consecutive  numbers  running 
from  1  to  186.  The  grade  of  wood  used  for  each  panel  was 
indicated  by  an  abbreviated  mark  —  W  for  white  pine,  C  for 


SCOPE  OF  PRACTICAL  PAINT  TESTS  107 

cypress,  and  Y  for  yellow  pine.  In  order  that  a  record  of  each 
panel  might  be  kept  on  file,  previous  to  the  application  of  paint 
to  the  panels,  a  complete  series  of  photographs  was  taken  of  the 
panels  in  sets  of  four.  This  work  seemed  advisable  so  that  the 
future  failure  of  paint  on  any  one  panel,  which  might  be  thought 
due  to  faulty  wood,  could  be  either  verified  or  refuted  by  a  refer- 
ence to  the  series  of  photographs  made  of  the  bare  panels. 

Construction  of  Panels.  The  panels  were  constructed  of 
Dutch  weather  boarding,  tongued  and  grooved  together  in  strips 
of  three  pieces  and  capped  at  the  top  with  a  weather  strip, 
forming  a  finished  surface  three  feet  long  and  fifteen  and  a  half 
inches  high.  They  were  firmly  braced  together  at  their  backs 


View  of  Atlantic  City  Test  Fence 

and  nailed  in  such  a  manner  that  no  portion  of  the  nails  would 
appear  on  the  surface  of  the  panel,  thus  preventing  the  staining 
of  the  panel  from  rust.  The  construction  of  the  framework  of 
the  fences  at  Atlantic  City  and  Pittsburg  was  of  such  a  nature 
that  they  would  each  accommodate  560  panels  of  this  type. 

Starting  of  Tests.  On  account  of  the  lateness  of  the  season, 
it  was  found  necessary  to  do  the  painting  of  the  tests  within  a 
building,  so  that  each  formula  might  be  subjected  to  fair  and 
equal  conditions  of  application,  thus  excluding  the  blowing  of 
dust  or  rain  upon  the  painted  surfaces,  which  would  have  taken 
place  had  the  panels  been  painted  upon  the  fence.  The  painting 
of  the  panels  began  in  January,  1908,  the  temperature  within 
the  buildings  in  which  the  work  was  done  averaging  50  degrees 
Fahrenheit  throughout  the  work. 

It  was  decided  to  test  each  formula  in  three  colors,  in  duplicate, 
and  on  each  grade  of  wood,  exposing  the  duplicates  on  either 


108 


PAINT   TECHNOLOGY  AND   TESTS 


side  of  the  fence.     Thus  for  one  paint  formula  there  were  required 
18  panels,  or  6  painted  in  each  color  and  on  3  grades  of  wood. 

Paints  for  Tests.  The  mixed  paints  received  for  the  tests 
were  in  quart  cans,  having  been  especially  prepared  from  the 
formulas  submitted  to  manufacturers  by  the  technical  com- 
mittee in  charge  of  the  work.  They  were  properly  labeled  with 
their  number  and  color,  in  each  case.  The  formulas  decided 
upon  for  the  test  are  described  later.  The  various  white  leads 
and  other  single  pigment  paints  which  were  used  were  received 
in  kegs  weighing  12J  pounds  each,  having  been  bought  in  the  open 
market  and  then  given  a  formula  number.  The  formulas  of 
the  paints  designed  for  both  the  Atlantic  City  and  Pittsburg 
tests,  as  well  as  the  numbers  of  the  panels  upon  which  the  paints 
were  applied,  are  shown  on  pages  131-133-145.  The  analysis 
of  one  of  the  combination  paints  applied  is  herewith  given,  to 
show  the  correct  method  of  stating  the  composition  of  a  paint. 

FORMULA  No.  20,  ATLANTIC  CITY  TEST  FENCE 
Percentage  Composition 


Pigment 

Vehicle 

Total 

Corroded  white  lead 

67.01 

42.84 

Zinc  oxide 

19.89 



12.71 

Asbestine  . 

3.86 



2.47 

Calcium  carbonate  
Raw  oil  
Japan  drier  
Turpentine  

9.24 

94.30 
3.89 
1.81 

5.91 
34.02 
1.40 
0.65 

100.00 

100.00 

100.00 

Brushes.  Heavy  7-O  round  bristle  brushes  were  used  for 
the  priming  coat  so  that  the  paint  might  be  well  worked  into 
the  wood,  while  for  the  second  and  third  coats  three-inch  chisel 
edge  brushes  were  used.  These  brushes  were,  of  course,  washed 
several  times  with  turpentine  after  painting  each  panel,  so  that 
pigments  from  one  paint  could  not  be  carried  over  into  a  paint 
containing  other  pigments. 

Shellacking  Panels.  The  shellacking  of  any  bad  places  of 
minor  nature  which  may  have  been  present  on  the  surfaces  of 
some  of  the  panels,  wTas  done  with  the  highest  grade  orange 
shellac.  It  was  thought  advisable  to  determine  whether  shel- 
lacking over  the  priming  coat  of  paint  or  on  the  bare  wood 


SCOPE  OF  PRACTICAL   PAINT   TESTS 


109 


Cypress  Panels 


110  PAINT  TECHNOLOGY  AND   TESTS 

previous  to  the  application  of  the  priming  coat,  was  the  better 
method.  Panels  Nos.  1  to  8  in  each  test  were  therefore  shel- 
lacked over  the  priming  coat,  while  on  all  other  panels  the 
shellacking  was  done  directly  on  the  bare  wood  previous  to  the 
application  of  the  priming  coat  of  paint. 

Application  of  Paints.  In  order  to  determine  just  how  much 
paint  was  applied  to  each  panel  and  to  reckon  the  spreading  rate 
therefrom,  careful  weighings  were  made  during  the  application 
of  every  paint.  This  was  carried  out  by  placing  a  quart  can  of 
paint  as  received,  upon  a  laboratory  balance,  the  gross  weight 
being  taken  and  recorded.  The  can  was  shaken  and  its  contents 
transferred  to  a  quart-size  enameled  cup  where  with  the  aid  of 
a  paddle  it  was  broken  up  into  a  mixture  of  even  consistency. 
A  portion  of  this  paint  was  then  transferred  to  two  small  sample 
cans  carefully  numbered  with  the  formula  number,  for  future 
reference  and  analysis.  The  reduction  of  the  paint  was  then 
made.  The  brush  used  on  the  priming  coat  was  placed  with 
the  pot  and  the  paint  on  the  balance  and  the  weight  taken  by 
the  official  weigher.  The  pot  was  then  given  to  the  painter  who 
applied  the  priming  coat  to  one  panel.  The  brush,  pot,  and 
paint  were  then  handed  back  to  the  official  weigher  and  the 
difference  in  weight  recorded.  From  these  data  could  be  reck- 
oned the  spreading  rate  of  the  formula  applied. 

The  drying  of  the  panels  was  noted  every  few  hours  and 
observations  made  to  determine  whether  the  paints  were  pene- 
trating properly  into  the  surface  of  the  wood.  A  period  of  eight 
days  was  allowed  between  each  coat  in  order  that  thoroughly 
hard  setting  might  take  place. 

During  the  application  of  the  second  coat  of  paint  to  the 
panels,  fresh  cans  of  paint  were  used  in  every  case  so  that  fresh 
reductions  could  be  made  of  the  proper  consistency.  Full  data 
were  also  recorded  on  the  ease  of  application,  working,  and  nature 
of  drying  shown,  as  well  as  appearance  presented  by  each  paint 
after  each  coat  had  been  applied.  New  packages  of  paint  were 
also  used  for  the  third  coat,  and,  as  a  rule,  the  paint  was  applied 
without  reduction  or  with  full  oil  reduction,  turpentine  being 
eliminated  in  nearly  every  case  for  the  third  coat  work. 

Reductions.  The  single  pigment  paints,  such  as  white  leads, 
were  reduced  by  the  so-called  ounce  system,  each  ounce  of  oil 
added  to  12|  ounces  of  paste  pigment  representing  one  gallon 


SCOPE  OF  PRACTICAL  PAINT   TESTS  111 

of  vehicle  to  one  hundred  pounds  of  lead.  A  complete  report  of 
the  reductions,  spreading  rates,^etc.,  used  in  the  tests  would  take 
up  three  or  four  hundred  pages  of  printed  matter.  The  reduc- 
tions shown  on  the  following  formulas  are,  however,  fairly 
representative  of  the  reductions  used  on  the  combination  and 
single  pigment  paints. 

REDUCTIONS  ON  FORMULA  No.  2 

White  and  Yellow 

1st  Coat 

Condition  when  opened  —  good. 
Consistency  when  broken  up  —  heavy. 
Reduction  recommended  by  manufacturer  —  none. 
Reduction  used  —  3  pints  raw  oil  1  pint  turps,  1  gallon  paint. 
Consistency  after  reducing  —  good,  stiff. 
Working  —  fair. 

Drying  —  fair  on  pines;   cypress  —  poor. 
Penetration,  pines  —  good;  cypress  —  poor. 

2nd  Coat 

Consistency  when  broken  up  —  heavy. 
Reduction  used  —  If  pints  turpentine,  1  pint  boiled  oil. 
Consistency  after  reducing  —  good. 
Working  —  good. 
Hiding  —  medium. 

Drying  on  pines  —  good;  cypress  —  poor.  One-half  pint  japan  added  to 
gallon  of  paint. 

Penetration  —  fair. 

3rd  Coat 
Reduction  used  —  1|  pints  oil,  \  pint  turpentine. 

Reductions  for  Lead  Pastes 
Calculated  on  100  Ib.  keg. 

Formulas  Nos.  37-38.      (Corroded  White  Lead.) 

1st  Coat 
6|  gallons  oil,  \  gallon  turpentine,  1  pint  turpentine  japan. 

2nd  Coat 
3£  gallons  oil,  1  gallon  turpentine,  1  pint  japan. 

3rd  Coat 
3  gallons  oil,  1  pint  turpentine,  \  pint  japan. 

Hiding  Power  of  Paints.  When  the  priming  coat  had  thor- 
oughly dried  on  each  panel,  the  painter  carefully  stencilled  a 
black  Geneva  cross  over  the  priming  coat  with  lampblack  in  oil. 
The  object  of  this  black  cross  was  to  make  a  determination  of 


112  PAINT  TECHNOLOGY  AND   TESTS 

the  comparative  opacity  or  hiding  power  of  the  different  paints 
applied.  It  is  well  known  that  various  pigments  when  ground 
in  oil  differ  in  their  hiding  power  in  direct  proportion  to  the 
difference  in  the  refractive  indices  of  the  pigments  and  oils  used, 
those  containing  high  percentages  of  pigments  such  as  white 
lead  and  zinc  oxide  being  superior  in  hiding  power.  After  the 
second  and  third  coat  of  paint  had  been  applied  to  each  panel, 
there  was  evident  a  remarkable  difference  in  the  hiding  power, 
as  the  black  cross  showed  through  in  some  cases  quite  clearly, 
while  in  other  cases  it  was  almost  completely  hidden.  The 
hiding  power  of  a  paint  is  one  of  the  properties  which  the  master 
painter  looks  upon  as  most  essential,  but  it  should,  of  course,  be 
accompanied  in  a  satisfactory  paint  by  good  spreading  power  and 
longevity. 

Actinic  Light  Tests.  After  the  drying  of  all  the  paints,  it 
was  decided  that  it  would  be  of  extreme  interest  to  conduct  a 
test  on  the  resistance  of  certain  paints  to  actinic  light.  It  is 
well  known  that  the  ultraviolet  or  chemical  rays  of  the  sun  are 
most  energetic  in  causing  chemical  reactions  that  result  in  the 
early  decay  of  certain  types  of  paint.  It  was  thought  that  the 
disintegrating  effect  of  these  rays,  as  well  as  their  effect  in 
the  bleaching  out  of  colors,  might  be  prevented  by  placing 
upon  certain  panels  small  orange  colored  glass  slides  which  would 
prevent  the  passing  of  these  rays  to  the  painted  surface.  The 
slides  used  were  five  inches  long  and  three  inches  wide  and  were 
placed  upon  the  middle  board  of  certain  panels,  with  picture 
framing,  putty,  and  galvanized  iron  tacks.  The  preservation  of 
the  underlying  surface  from  the  sun's  rays  would,  it  was  thought, 
prevent  the  deterioration  of  the  paint,  and  at  the  same  time 
preserve  its  original  color  so  that  it  might  be  compared  to  the 
color  of  the  exposed  portion  at  the  time  of  inspection. 

Supervision  of  Tests.  The  Atlantic  City  tests  were  under 
the  constant  supervision  of  Committee  E  of  the  American 
Society  for  Testing  Materials,  this  committee  having  accepted 
the  inspection  of  the  fence.  A  representative  was  constantly 
present  throughout  the  work  in  order  to  see  that  each  formula 
received  fair  treatment.  The  actual  painting  work  was  under 
the  supervision  of  the  writer,  together  with  a  master  painter 
representing  George  Butler  who  was  chosen  by  the  Master 
Painters'  Association  of  Philadelphia  as  the  official  painter  of 


SCOPE  OF  PRACTICAL  PAINT  TESTS  113 

the  Atlantic  City  test  fence.  Mr.  J.  B.  Campbell  of  Chicago 
also  acted  as  an  official  of  the  Paint  Manufacturers'  Association 
in  the  application  of  the  formulas  to  both  the  Atlantic  City  and 
Pittsburg  fences. 

At  Pittsburg  the  fence  was  placed  directly  under  the  super- 
vision and  control  of  the  Carnegie  Technical  Schools,  who  chose 
for  the  fence  work  a  committee  of  their  technical  force.  Drs. 
James  and  Schaeffer  of  this  institution  were  present  throughout 
most  of  the  work  and  were  constantly  represented  during  the 
test.  The  Pittsburg  Master  Painters'  Association  appointed  a 
committee  consisting  of  Messrs.  Dewar,  Rapp,  and  Cluley,  for 
the  actual  painting  work,  and  they  were  represented  with  the 
writer  throughout  the  tests. 

Great  interest  was  exhibited  in  the  work  by  the  committees 
in  charge,  and  the  skill  of  the  practical  painters,  combined  with 
the  care  of  the  inspectors,  made  the  treatment  of  each  formula 
fair  and  satisfactory. 


CHAPTER   VII 
CONDITIONS   NOTED   AT  INSPECTION   OF  TESTS 

Inspection  of  Atlantic  City  Tests.  During  the  month  of 
March,  just  one  year  after  the  placing  of  the  painted  panels  on 
the  Atlantic  City  fence,  an  inspection  was  made  jointly  by  a 
committee  representing  the  Master  Painters'  Association  of 
Pennsylvania,  the  Scientific  Section  of  the  Paint  Manufacturers' 
Association  of  the  United  States,  and  certain  members  of  sub- 
Committee  E  of  the  American  Society  for  Testing  Materials. 

Methods  Used  at  Inspection.  One  of  the  most  important 
tests  made  when  inspecting  paint  is  the  determination  of  the 
chalking  taking  place.1  There  was  developed  during  the  inspec- 
tion of  the  Atlantic  City  panels  a  new  method  for  determining 
the  comparative  chalking  of  the  various  paints.  It  was  thought 
desirable  to  secure  a  method,  if  possible,  that  would  show  results 
which  might  be  photographed  and  even  tabulated  in  percentage 
form,  if  desired.  The  apparatus  for  the  new  test  consisted  of  a 
small  strip  of  black  felt  three  inches  wide  by  five  inches  long, 
placed  across  a  small  block  of  wood  which  would  fit  in  the  palm 
of  the  inspector's  hand.  This  outfit  resembled  a  blackboard 
eraser  and  was  used  in  a  similar  way.  By  holding  the  apparatus 
firmly  against  the  panel  and  drawing  it  half-way  across  the  panel 
in  a  straight  line  toward  the  operator,  there  was  obtained  on  the 
black  cloth  a  white  mark  proportional  in  intensity  to  the  amount 
of  chalking  which  had  taken  place  on  the  given  area.  When  a 
series  of  these  cloths  were  made,  they  were  assembled  and  photo- 
graphed for  comparison.  It  should  be  noted  that  the  above 
chalking  test  is  useful  only  where  the  painted  panels  under 
examination  have  been  exposed  over  a  period  of  one  to  two 

1Mr.  Macgregor  of  the  Picher  Lead  Co.  has  just  developed  a  new  test 
to  determine  the  relative  imperviousness  of  paints  which  have  begun  to 
chalk.  He  draws  a  mark  about  two  inches  long  upon  the  painted  surface 
with  a  fountain  pen.  The  ink  mark  will  spread  rapidly  to  a  wide  area  if 
the  chalking  is  of  a  bad  order.  If  the  chalking  is  slight  and  the  film  in 
good  condition,  the  ink  mark  will  not  spread. 

114 


CONDITIONS  AT  INSPECTION  OF   TESTS 


115 


118         PAINT  TECHNOLOGY  AND  TESTS 


\ 


BLISTERING. —Type  of  Decay  Exhibited  by   Improperly  Made  Paint 

(magnified  view) 


CONDITIONS  AT  INSPECTION  OF  TESTS  119 


CRACKING.  —  Type  of  Decay  Exhibited  by  Improperly  Made  Paint 

(magnified  view) 


PAINT  TECHNOLOGY  AND  TESTS 


BLISTERING. —Type  of  Decay  Exhibited  by   Improperly  Made  Paint 

(magnified  view) 


CONDITIONS  AT  INSPECTION  OF  TESTS  119 


CRACKING. —Type  of  Decay  Exhibited  by  Improperly  Made  Paint 

(magnified  view) 


120 


PAINT  TECHNOLOGY  AND   TESTS 


GENERAL    DISINTEGRATION.  —  Type    of   Decay   Exhibited   by 
Improperly  Made  Paint   (magnified  view) 


CONDITIONS  AT  INSPECTION  OF   TESTS 


121 


SCALING.  —  Type    of    Decay   Exhibited    by    Improperly    Made   Paint 

(magnified  view) 


122  PAINT  TECHNOLOGY  AND   TESTS 

years,  during  which  period  the  chalking  of  paints  has  been  shown 
to  be  greatest  and  the  chalked  surface  of  a  fairly  adherent  nature. 
Where  longer  exposures  have  been  made  and  where  rains  have 
removed  from  the  painted  panels  a  considerable  amount  of  the 
chalked  pigment  which  has  formed,  such  a  test  would  not  be 
fairly  representative  of  the  amount  of  chalking  which  had  taken 
place. 

Gloss.  The  gloss  of  the  various  panels  was  a  condition  which 
was  also  reported  upon,  the  middle  board  of  each  panel  being 
washed  with  a  wet  sponge  one  day  before  the  inspection  so  that 
any  surface  dirt  might  be  removed.  By  looking  at  a  panel 
from  the  side,  a  day  after  the  washing,  the  inspector  was  enabled 
to  get  a  fair  idea  of  the  degree  of  gloss  exhibited  by  each  formula. 

Hiding  Power.  The  hiding  power  of  each  paint  was  deter- 
mined, as  before  described,  by  observing  the  degree  to  which 
the  stencilled  lampblack  cross  on  the  priming  coat  was  visible 
through  the  second  and  third  coats.  Single  pigment  paints 
such  as  white  lead  possessed  very  great  hiding  power  and  ob- 
scured the  black  cross  almost  completely,  while  the  cross  was 
quite  visible  through  paints  containing  high  percentages  of 
crystalline  pigments. 

Checking.  The  checking  of  each  panel  was  determined  by 
examining  with  a  small  high-power  hand  glass  magnifying  fifteen 
diameters.  It  is  well  known  that  examinations  with  such  a 
hand  glass  will  not  determine  whether  so-called  finejmatt  check- 
ing is  taking  place,  but  it  will  determine  whether  checking  has 
appeared  to  any  marked  extent.  Fine  matt  checking  is  the 
first  sign  of  the  decomposition  of  a  paint,  and  is  preliminary  to 
the  visible  checking  seen  by  the  naked  eye,  which  is  often  followed 
by  alligatoring.  Examination  of  some  formulas  disclosed  this 
so-called  alligatoring  and  even  the  exposed  wood  between  the 
fissured  surface  which  had  developed  from  what  were  at  first 
fine  hair  checks.  It  is,  in  the  opinion  of  the  writer,  possible  to 
predict  with  a  fair  degree  of  accuracy  by  examination  of  a  painted 
surface,  one  year  after  exposure,  how  the  paint  will  wear  in  the 
future  and  what  its  appearance  will  be  at  the  end  of  another 
year. 

Hardness.  The  hardness  of  each  panel  could  not  be  deter- 
mined with  any  degree  of  accuracy,  but  the  inspectors  were  able 
to  roughly  determine  this  condition  by  very  close  inspection. 


CONDITIONS  AT  INSPECTION  OF  TESTS  123 

From  practical  experience  of  the  wearing  of  white  lead  and  zinc 
oxide,  and  the  comparative  hardness  of  these  two  pigments, 
zinc  oxide  was  selected  as  the  maximum  for  hardness  and  termed 
number  10,  while  w^hite  lead  was  selected  as  the  minimum  and 
termed  number  1.  The  varying  degrees  of  hardness  exhibited 
by  the  formulas  were  recorded  in  terms  from  one  to  ten.  This 
comparison  of  course  was  only  an  approximate  one. 

General  Condition.  The  so-called  general  conditions  of  the 
panels  was,  as  a  rule,  the  consensus  of  the  judgment  held  by 
the  various  inspectors,  with  due  regard  to  such  properties  as 
chalking,  checking,  gloss,  hiding  power,  color  maintenance, 
condition  of  surface,  etc. 


CHAPTER   VIII 
RESULTS   OF  ATLANTIC   CITY  TESTS 

Results  on  Various  Woods.  On  the  Atlantic  City  Fence  all 
the  tests  made  on  yellow  pine  and  cypress  were  found  to  be  in 
an  unsatisfactory  condition  for  a  report,  for  in  every  case  the 
sap  and  small  knots  contained  in  such  wood  had  a  very  bad  effect 
upon  the  paint,  causing  peeling  and  scaling.  The  white  pine 
panels  were  in  very  much  better  condition,  and  it  was  therefore 
decided  to  make  the  inspection  entirely  from  the  white  pine 
panels  and  in  the  future  to  remove  the  yellow  pine  and  the 
cypress  panels  from  the  fence  and  from  the  test.  The  Com- 
mittee advised  that  all  future  tests  be  made  on  white  pine,  as 
it  is  obviously  unfair  to  use  anything  but  the  highest  grade  wood 
for  a  paint  test  in  which  the  desire  is  to  determine  -the  com- 
parative wearing  value  of  pigments. 

Paints  Containing  Lithopone.  One  of  the  most  striking  ex- 
hibitions of  paint  disintegration  in  the  whole  test  was  the  failure 
of  nearly  all  the  lithopone  formulas  tested.  At  the  time  these 
formulas  were  suggested  for  the  test,  various  European  technical 
journals  had  advocated  the  use  of  lithopone  in  large  percentage 
for  paints  to  be  used  on  exterior  surfaces.  Good  results  had 
been  obtained  in  the  northwestern  section  of  Europe,  with  this 
pigment  in  certain  mixtures,  and  the  object  of  these  lithopone 
tests  at  Atlantic  City  and  Pittsburg  was  to  determine  whether 
satisfactory  paints  could  be  made  of  this  pigment  for  exposure 
in  this  country.  Failure  of  the  tests,  however,  in  nearly  every 
case  except  where  zinc  oxide  and  whiting  were  mixed  with  the 
lithopone,  indicated  that  pigments  such  as  zinc  and  whiting  are 
necessary  in  order  to  prevent  the  decomposition  of  lithopone 
pigment  paints.  The  decay  of  lithopone  paints  after  they  are 
applied  seems  to  start  with  rapid  oxidation  of  the  linseed  oil, 
and  this  oxidation  seems  to  continue  in  a  progressive  and  even 
accelerated  way;  after  six  months'  exposure  the  surface  of  the 

NOTE.  —  Recent  tests  have  shown  that  Cypress  may  be  successfully  painted  when  the 
priming  coat  of  paint  is  thinned  with  Benzol  (Solvent  Naphtha). 

124 


RESULTS   OF  ATLANTIC   CITY   TESTS 


125 


es 

05  '3 


.t3  o 


126 


PAINT    TECHNOLOGY  AND    TESTS 


RESULTS   OF   ATLANTIC   CITY   TESTS 


127 


2  * 

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- 1 

fa 

O  JES 

•si 

II 

2 


128  PAINT  TECHNOLOGY  AND   TESTS 

paint  being  chalked  to  a  great  extent  and  showing  rapid  de- 
composition of  the  binder  or  vehicle.  Inasmuch  as  lithopone 
is  really  an  inert  pigment,  this  rapid  decomposition  of  its 
vehicle  cannot  be  explained  in  the  same  way  as  the  decompo- 
sition of  the  vehicle  of  pure  white  lead  paints,  where  the  alka- 
line nature  of  the  lead  is  probably  responsible  for  the  formation 
of  easily  destroyed  compounds.  As  complete  failure  had  taken 
place  in  nearly  every  case  where  lithopone  had  been  used,  it  was 
decided  to  condemn  the  lithopone  panels  on  the  fence,  consist- 
ing of  formulas  21  to  27,  including  panels  151  to  164  in  white, 
panels  131  to  144  in  yellow,  and  109  to  122  in  gray.  These 
lithopone  tests  were  later  on  replaced  by  new  tests  in  1909, 
which  will  be  reported  upon  later  in  this  book. 

General  Results.  From  these  tests,  the  inspectors  reached 
the  unanimous  conclusion  that  a  paint  made  from  any  mixture 
of  more  than  one  white  opaque  pigment,  either  when  used  alone 
or  in  combination  with  small  percentages  of  inert  pigments, 
is  far  superior  to  any  one  single  pigment  paint.  It  was  found 
that  the  straight  white  lead  paints  failed  in  every  case,  and  this 
failure  was  so  marked  as  to  make  it  a  conclusive  demonstration 
of  the  unfitness  of  white  lead  along  the  Atlantic  coast,  when 
used  without  other  pigments.  Paints  made  with  large  percen- 
tages of  white  lead,  however,  gave  excellent  results. 

Gypsum  was  found  unsafe  to  use  in  any  large  proportion  in 
a  paint,  because  of  its  solubility  and  liability  to  percolate  through 
the  coating  of  linoxyn  or  dried  film,  thus  destroying  the  surface 
of  the  paint.  Whiting,  or  calcium  carbonate,  demonstrated 
that  it  could  be  used  in  moderate  percentage  with  some  efficiency, 
but  it  was  evident  that  any  great  excess  of  this  pigment  must  also 
be  avoided  on  account  of  its  tendency  towards  rapid  chalking. 
Magnesium  silicate,  aluminum  silicate,  and  silica  are  three 
inert  pigments  which  proved  to  be  of  great  value  in  strengthen- 
ing and  reinforcing  paints,  especially  when  they  were  used  in 
small  percentage.  In  the  same  way,  black  fixe  and  barytes,  or 
barium  sulphate,  also  appeared  to  be  useful  in  strengthening  a 
paint.  As  these  two  last  named  pigments  are  chemically  the 
same  but  physically  different,  the  use  of  both  in  a  paint  formula 
is  considered  advantageous,  because  of  the  differences  in  size 
and  form  of  their  particles. 

Color  Tests.     It  was  the  unanimous  conclusion  of  all  the 


RESULTS  OF  ATLANTIC  CITY  TESTS  129 

inspectors  that  panels  of  all  formulas  which  were  tinted  either 
gray  or  yellow  were  showing  far  superior  wear  and  less  chalking 
and  checking  than  those  which  were  painted  in  plain  white. 
The  reinforcing  action  of  the  tinting  materials  must  be  credited 
for  this  lengthening  of  the  wear  of  such  paints.  Formulas  5, 
6,  9,  and  16,  for  instance,  in  the  gray,  were  in  most  excellent 
condition,  and  in  these  formulas  were  used  ochre,  umber,  bone- 
black,  carbon-black,  Venetian  red  and  other  inert  bases.  On 
the  yellow  panels,  formulas  5,  6,  9,  and  16  were  also  in  very 
superior  condition,  and  in  these  formulas  chrome  yellow  and 
inert  pigments  were  also  used. 

Some  of  the  color  tests  included  the  priming  of  boards  with 
white  lead,  zinc  oxide,  sublimed  white  lead,  lithopone,  and  other 
single  pigment  paints.  Over  these  priming  coats  was  placed  a 
high  grade  brilliant  paranitraniline  red.  Fairly  good  results 
were  obtained  in  every  case,  but  especially  when  lithopone  or 
zinc  oxide  was  used  as  a  priming  base.  These  pigments  seemed 
to  have  no  effect  upon  the  constitution  of  the  para  red. 

Prussian  blue,  a  colored  pigment  largely  used,  but  one  liable 
to  react  with  certain  paint  pigments,  was  admixed  with  various 
paints  applied  to  certain  panels.  This  color  was  found  in  some 
cases  to  have  faded  materially,  especially  when  mixed  with  alka- 
line pigments  such  as  white  lead.  Sublimed  white  lead  and  zinc 
oxide,  which  are  more  inert  in  nature,  did  not  have  such  action 
on  Prussian  blue,  and  the  tinted  bases  of  these  pigments  stood 
up  in  a  remarkable  manner.  The  greens  which  were  tested 
were  all  in  very  good  condition,  with  absence  of  fading,  and 
showing  only  slight  mildew. 

Condensed  Results  of  Inspection.  The  results  of  inspection 
as  obtained  by  the  fence  committee1  having  in  charge  the  in- 
spection of  the  test,  have  been  condensed  into  table  form,  and 
are  presented  on  pages  130-131. 

Second  Annual  Inspection  of  the  Atlantic  City  Test  Fence. 
After  the  original  paints  which  had  been  applied  to  the  Atlantic 
City  Fence  had  been  exposed  for  over  two  years,  another  inspec- 
tion was  made  by  a  committee  representing  the  Master  Painters' 
Association  of  Philadelphia  and  the  Scientific  Section  of  the 

1  R.  S.  Perry,  Director  Scientific  Section,  Paint  Manufacturers'  Associa- 
tion of  the  U.  S.;  George  Butler,  Official  Painter,  representing  Master  House 
Painters'  &  Decorators'  Association,  H.  A.  Gardner,  Asst.  Director. 


130 


PAINT  TECHNOLOGY  AND  TESTS 


Paint    Manufacturers'    Association    of   the    United    States.     A 
digest  of  the  report  of  this  committee1  follows: 

"  The  painted  panels  were  all  carefully  inspected  by  the  inspec- 
tors in  the  usual  manner.  With  the  aid  of  high-power  magnify- 
ing glasses,  checking  was  determined.  The  degree  of  chalking 
exhibited  by  the  various  paints  was  ascertained  by  rubbing  a 
piece  of  black  cloth  across  the  surface  of  each  paint.  Close 
observance  was  made  to  determine  scaling,  peeling,  cracking, 
gloss,  color,  and  the  other  factors  to  be  considered  when  examining 
a  painted  surface.  From  these  observations  it  was  possible  for 

1  George  Butler,  Official  Painter  Atlantic  City  Test  Fence,  representing 
Philadelphia  Master  Painters'  Association;  Charles  Macnichol,  Master 
Painter;  Henry  A.  Gardner,  Director  Scientific  Section,  Paint  Manufac- 
turers' Association  of  the  U.  S. 

CHART    OF    RESULTS  — FIRST    INSPECTION  — 


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172 

RESULTS  OF  ATLANTIC  CITY  TESTS 


131 


the  inspectors  to  state  whether  a  panel  exhibited  general  good 
condition,  general  fair  condition,  or  general  poor  condition. 

"  An  inspection  of  the  white  lead  paints  on  the  fence  indicated 
in  every  instance  a  rough,  chalked,  and  disintegrated  surface 
that  seemed  to  be  well  worn,  in  some  cases  nearly  to  the  wood. 
The  strongly  oxidizing  air  of  the  seacoast  is  probably  responsible 
for  the  early  decay  of  this  pigment. 

"  It  was  observed  that  the  combination  type  of  paint  showed 
better  hiding  power  than  white  lead,  over  the  black  crosses  placed 
on  the  priming  coat  of  each  panel,  as  a  hiding  power  test. 

"  There  are  no  pigments  possessing  greater  hiding  properties 
when  first  used  than  white  leads,  but  the  lack  of  hiding  power 
on  the  white  lead  panels  after  two  years'  exposure  was  caused 
by  the  chalking  away  of  the  lead.  The  superior  hiding  power 

ATLANTIC    CITY    TEST    FENCE 


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132 


PAINT    TECHNOLOGY   AND    TESTS 


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RESULTS  OF  ATLANTIC  CITY   TESTS 


133 


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134  PAINT  TECHNOLOGY  AND   TESTS 

of  the  composite  paints  was  due  to  the  action  of  the  other  pig- 
ments in  these  combination  paints  in  preventing  the  lead  from 
chalking  away. 

"  The  Committee  finds  that  the  addition  of  a  reasonable  per- 
centage of  zinc  oxide  to  white  lead  increases  its  durability  and 
retards  its  chalking,  renders  it  whiter,  and  forms  a  surface  that 
presents  a  much  better  repainting  condition.  The  combinations 
of  white  lead  and  zinc  oxide  on  the  Atlantic  City  Test  Fence 
were  in  general  good  condition  throughout. 

"  Corroded  white  lead,  sublimed  white  lead,  zinc  oxide,  and 
zinc  lead  are  the  standard  white  opaque  pigments.  They  were 
all  tested  on  the  Atlantic  City  Fence  and  it  was  found  that  to 
use  any  one  alone  results  in  inferior  protection  to  the  wood. 
Barium  sulphate,  silica,  asbestine,  china  clay,  and  calcium  car- 
bonate are  the  standard  crystalline  pigments.  In  the  past, 
the  overloading  of  paints  with  these  crystalline  or  inert  pigments 
has  been  the  cause  of  the  prejudice  that  painters  have  had 
against  their  use.  It  has  been  established  beyond  controversy, 
however,  that  the  use  of  these  pigments,  in  moderate  percentage, 
combined  with  any  of  the  standard  opaque  white  pigments, 
such  as  white  leads,  zinc  oxide,  etc.,  undoubtedly  results  in 
better  service  from  every  standpoint  and  forms  the  most  satis- 
factory white  paint  for  general  outside  use.  Some  of  the  most 
perfect  painted  surfaces  on  the  fence  were  those  made  on  the 
above  basis  as  reference  to  the  charted  report  will  show." 


CHAPTER  IX 
RESULTS   OF  PITTSBURG  TESTS 

THE  First  Annual  Inspection  of  the  Pittsburg  Test  Fence 
took  place  during  May,  1909,  a  little  over  one  year  after  the 
painted  panels  had  been  placed  in  position.  The  inspectors 
found  that  in  Pittsburg  a  heavy  deposit  of  soot  had  formed  On 
the  panels,  and  they  considered  it  therefore  inadvisable  to  make 
a  detailed  report  of  the  inspection  until  the  second  year  of  the 
exposure.  The  general  results  of  the  Pittsburg  inspection  as 
reported  by  the  three  committees1  having  supervision  over  the 
work,  is,  however,  given  herewith. 

During  the  inspection  of  the  Pittsburg  tests  it  was  decided 
to  condemn  the  lithopone  panels  on  the  fence,  which  consisted 


Pittsburg  Test  Fence 

of  formulas  21  to  27,  including  panels  151  to  164  in  white,  131 
to  144  in  yellow,  109  to  122  in  gray.  Almost  complete  failure 
had  taken  place  in  every  case  where  lithopone  had  been  used. 
These  lithopone  tests  were  later  on  replaced  by  new  tests  which 
are  described  later  in  this  book. 

"Wood  Most  Valuable  for  Test.  As  on  the  Atlantic  City 
Fence,  the  white  pine  panels  afforded  the  best  results  and  gives 
the  best  indication  of  the  comparative  wearing  of  the  paints  and 
affords  no  unfair  condition,  such  as  other  woods  might  offer,  to 
interfere  with  the  test. 

1 J.  H.  James,  Chairman  Test  Fence  Committee,  Carnegie  Technical 
Schools. 

A.  C.  Rapp,  Chairman  Fence  Committee,  Pittsburg  Branch  Pennsylvania 
State  Association  of  Master  Painters. 

R.  S.  Perry,  Director  Scientific  Section,  Paint  Manufacturers'  Association 
of  the  U.  S.;  H.  A.  Gardner,  Asst.  Director. 

135 


136  PAINT  TECHNOLOGY  AND   TESTS 

"  Condition  of  Cypress.  Cypress  showed  inferior  conditions, 
except  that  it  was  more  pronounced  and  more  discoloration  of 
the  panels  was  noticed  on  this  grade  of  wood,  which  seems  to  be 
extremely  greasy  in  nature  and  difficult  to  properly  prime,  even 
when  the  paint  used  upon  this  wood  contains  a  large  percentage 
of  volatile  diluent. 

"  Removal  of  Lithopone  Panels.  The  Joint  Committees  con- 
firmed the  previous  recommendation  to  remove  all  the  lithopone 
formulas,  and  they  decided  to  remove  the  cypress  and  the  yellow 
pine  panels  in  every  formula  except  in  the  white  paints. 

"  It  was  decided  to  reassemble  all  the  white  pine  panels  and 
group  them  together  for  purposes  of  comparison,  and  in  place 
of  the  panels  condemned  and  removed,  to  substitute  a  series  of 
new  formulas,  to  further  widen  the  scope  of  the  tests. 

"  Ultimate  Value  of  Mixed  Paints.  The  results  of  the  inspec- 
tion conclusively  show  that  a  mixture  of  more  than  one  prime 
white  pigment,  whether  this  mixture  be  alone  or  in  combination 
with  a  small  percentage  of  inert  pigment,  produces  a  paint  far 
superior  to  a  paint  manufactured  from  one  pigment  alone. 

"  As  a  general  statement  of  the  comparative  wearing  of  the 
paints,  it  might  be  said  that  the  composite  formulas  are  less 
advanced  toward  destruction  than  the  paints  made  from  single 
pigments  such  as  lithopones,  white  leads  and  zinc  oxides.  It 
is  not  to  be  understood  from  this  statement  that  it  is  the  opinion 
of  the  committee  that  all  of  the  composite  formulas  are  of 
equal  value  or  that  all  of  them  are  to  be  recommended,  but  it 
is  meant  that  the  higher  types,  as  evidenced  by  the  appearance 
of  the  panels,  are  in  the  above  relation  to  the  single  pigment 
paints. 

"  Lithopone  Destroyed  Rapidly  at  Pittsburg.  It  was  evident 
some  time  ago  that  the  formulas  containing  large  percentages 
of  lithopone  were  rapidly  failing,  and  their  appearance  was  very 
much  the  same  as  those  formulas  of  a  similar  type  at  Atlantic 
City.  There  seems,  however,  to  be  some  difference  in  the  way 
these  formulas  broke  down;  those  on  the  Pittsburg  Fence  having 
shown  the  quicker  destruction,  possibly  due  to  the  action  of  the 
acid  gases  in  the  air  upon  the  paint  coating.  This  further  con- 
firms the  statement  that  paint  compositions  containing  such 
heavy  percentages  of  lithopone  and  intended  for  outside  use 


RESULTS  OF  PITTSBURG   TESTS 


137 


bO 

I 


138  PAINT  TECHNOLOGY  AND  TESTS 

must  be  designed  with  relation  to  the  particular  uses  of  the 
product  and  to  the  climate  in  which  they  are  to  be  used.  It 
will  also  be  necessary  to  consider  more  carefully  the  vehicle  of 
the  paints  which  are  to  be  made  of  this  pigment. 

"  Possible  Value  of  Excluding  Vehicle  for  Lithopone.  It  was 
the  belief  of  the  committee  that  much  better  paints  containing 
lithopone  could  be  designed  by  varying  the  percentages  of  the 
materials  contained  in  the  formulas,  and  it  was  suggested  that 
a  less  penetrable  vehicle,  made  more  on  the  line  of  a  varnish, 
and  not  as  easily  affected  as  straight  linoxyn,  should  be  experi- 
mented with  in  connection  with  these  lithopone  formulas. 

"  The  success  of  certain  European  countries  in  using  lithopone 
as  a  pigment,  even  in  a  very  high  percentage,  may  be  due  to  the 
use  of  a  special  vehicle,  and,  if  it  is  found  in  future  tests  that  this 
material,  which  has  been  reported  as  well  suited  in  Northern 
European  climates,  may  be  benefited  and  made  of  service  by 
the  addition  of  special  oils  and  special  vehicles,  then  this  test 
would  be  of  great  value  to  the  whole  paint  trade  at  large. 

"  Preliminary  inspections  were  made  on  October  6th  and 
later  on  December  12th,  1908,  and  a  marked  difference  was  ob- 
served at  the  two  inspections  in  the  wearing  of  the  various 
formulas. 

"  The  lapse  of  the  two  months  between  these  inspections  gave 
opportunity  during  which  cold  weather  caused  contraction  of 
the  paint  film  which  had  been  previously  subjected  to  the  hot 
summer  sun,  and  caused  marked  chalking  of  the  white  lead 
formulas.  On  October  6th  this  chalking  was  just  commencing, 
while  in  the  December  inspection  it  was  well  advanced,  and  at 
the  annual  inspection,  had  proceeded  to  such  an  extent  that  the 
pigment  had  been  washed  from  the  panels  representing  those 
paints  which  had  started  early  chalking. 

"  Panel  177,  representing  Zinc  Lead,  was  found  to  be  ex- 
tremely dark  in  color  throughout  the  coating  and  was  more  on 
the  order  of  a  grayish  tint.  It  resisted  all  attempts  to  wash  it 
down  to  a  white  surface.  The  panel,  however,  in  other  respects, 
was  in  fairly  good  condition. 

"  Condition  of  Corroded  White  Lead  Panels.  Panel  174, 
representing  Type  B  Pure  Basic  Carbonate-White  Lead,  was 
very  badly  perished  and  discolored,  and  an  examination  of  the 
surface  showed  very  bad  checking.  Long  continued  washing 


RESULTS  OF  PITTSBURG  TESTS  139 

with  a  sponge  removed  a  discolored  surface  and  showed  but  a 
rather  thin  coating.  Panel  175,  representing  Type  C  Pure 
Basic  Carbonate-White  Lead,  showed  most  marked  checking 
and  was  in  very  much  the  same  condition  as  174  and  176.  Panel 
176,  representing  Type  A  Pure  Basic  Carbonate-White  Lea'd, 
was  in  the  same  condition  as  the  Type  B  and  C  Basic  Carbonate- 
White  Leads. 

"  Condition  of  Sublimed  White  Lead.  Panel  178,  represent- 
ing Sublimed  White  Lead  (Basic  Sulphate-White  Lead,)  was 
chalking,  and  the  paint  coat  was  somewhat  disintegrated.  The 
chalking  present  on  this  formula,  however,  showed  that  the 
disintegration  of  the  paint  coat  had  not  taken  place  for 
several  months  after  the  Basic  Carbonate- White  Leads.  This 
panel  maintained  good  color,  not  being  acted  upon  by  sulphur 
gases. 

"  Blackening  of  Corroded  White  Lead.  The  black  and  gray 
formation  on  all  the  Basic  Carbonate -White  Lead  panels  was 
probably  due  to  the  action  of  sulphur  gases  which  are  present 
in  the  district  immediate  to  Pittsburg,  and  which  may  cause 
the  formation  of  black  sulphide  of  lead. 

"  Possibly  a  general  conclusion  from  all  these  panels  might  be 
described  as  a  perishing  of  the  paint  coating,  with  the  formation 
of  sulphide  of  lead  which  to  a  certain  extent  protects  the  coating 
beneath  it,  "but  the  perishing  has  proceeded  to  such  an  extent 
that  the  unaltered  paint  coating  left  is  but  a  slight  protection 
to  the  wood,  being  extremely  thin. 

"  The  committee  resolved  that  the  detailed  observations  of 
the  panels  could  not  be  made  and  that  they  would  not  be  justified 
in  making  detailed  comparisons  between  the  various  formulas, 
giving  the  gloss,  hardness,  general  condition,  checking,  etc. 
Precision  in  this  work  at  such  a  time  was  impossible,  and  it  was 
decided  that  a  further  period  would  have  to  elapse  before  such 
a  detailed  comparison  could  be  made  between  the  various  blended 
or  composite  formulas  on  the  fence. 

"  Report  on  Colors.  It  was  resolved  that  at  the  next  inspec- 
tion of  the  Pittsburg  Fence,  portions  of  the  original  samples  of 
the  original  paints  used  for  the  yellows  and  grays  should  be  on 
hand,  previously  painted  out  on  small  panels  for  comparison  for 
the  deterioration  of  the  colors  on  these  same  panels  on  the 
fence. 


140  PAINT   TECHNOLOGY  AND   TESTS 

"  An  examination  of  the  combination  formula  grays  by  the 
committee  led  to  the  general  conclusion  that  those  grays  which 
did  not  contain  a  very  large  percentage  of  white  lead  were  superior 
in  their  maintenance  of  tone  and  tint  and  general  condition  to 
any  of  the  other  grays  upon  the  fence.  However,  the  presence 
of  umber,  ochre,  and  red  oxide  in  some  of  the  grays  which  showed 
to  the  best  advantage  may  account  for  their  permanence  of  tone. 
Some  of  these  grays  were  the  so-called  warm  grays  and  were 
much  darker  in  tone  and  tint  than  the  ordinary  drab  which  is 
generally  applied. 

"  The  straight  pure  Basic  Carbonate- White  Lead  paints  were 
not  painted  out  in  grays  or  yellow,  the  test  upon  this  material 
being  only  in  white. 

"  On  Panels  120  and  126,  which  represent  formulas  6  and  9 
respectively,  the  grays  are  in  most  excellent  condition,  and  it 
will  be  found,  by  reference  to  formulas  6  and  9,  that  there  is  an 
absence  of  white  lead  in  their  composition.  These  formulas, 
however,  contained  a  small  percentage  of  umber  and  ochre. 
Formulas  5  and  16  contained  over  20%  White  Lead  and  the 
gray  of  these  formulas  maintained  their  blue  tone  very  well. 
These  formulas  were  tinted  solely  with  lampblack. 

"  An  inspection  of  Panel  138,  which  represents  Formula  15, 
showed  good  maintenance  of  color  in  the  gray,  and  was  in  much 
better  condition  as  regards  permanence  of  color  than  the  other 
grays  containing  white  lead. 

"  A  study  of  the  yellow  panels  on  the  fence  led  to  the  unani- 
mous conclusion  that  a  liberal  amount  of  Basic  Carbonate-White 
Lead  seemed  to  have  a  beneficial  result  in  preserving  the  bright 
tone  of  the  chrome  yellow  in  tints  so  strong  as  those  used  on  the 
fence.  It  was  noted  that  Panel  108,  which  represents  Formula 
28,  and  in  which  zinc  yellow  was  used,  showed  great  permanence 
of  tone  and  tint.  Unfortunately  this  zinc  chromate  was  added 
to  a  formula  containing  a  large  percentage  of  lithopone,  and  the 
destruction  of  the  lithopone  to  a  great  extent  affected  the  value 
of  this  test.  . 

"  Maintenance  of  Para  Reds.  A  study  of  the  paranitraniline 
or  azo  reds  painted  over  the  various  pigments  as  priming  coats 
demonstrated  that  the  reds  on  this  fence  are  in  better  condition 
than  the  reds  at  Atlantic  City.  As  is  well  known,  para  red  is 
manufactured  by  precipitation  in  an  acid  solution  and  is  best 


RESULTS  OP  PITTSBURG   TESTS 


141 


142  PAINT  TECHNOLOGY  AND   TESTS 

maintained  under  acid  conditions.  The  acidity  of  the  Pittsburg 
atmosphere,  caused  by  the  large  amount  of  acid  gases  which  are 
being  poured  into  the  air,  day  in  and  day  out,  and  which  are 
constantly  condensing  on  the  surface  of  structures,  may  account 
for  the  better  preservation  of  these  reds. 

"  It  was  noted  that  the  para  reds  which  were  applied  to  panels 
prime  coated  with  white  lead  seemed  to  be  brightening  in  color 
and  seemed  to  be  gradually  working  over  toward  a  lightening 
which  may  in  the  future  show  a  pinkish  tint. 

"  Report  on  Greens.  The  bronze  green  is  in  most  excellent 
condition  and  shows  an  absence  of  the  mildew  appearance  which 
was  observed  at  Atlantic  City. 

"  The  chrome  green  is  standing  up  exceedingly  well,  there 
being  practically  no  change  whatsoever  in  the  color  since  it  was 
exposed. 

"  Best  Base  for  Blues,  An  inspection  of  the  blues  showed 
that  those  which  gave  the  greatest  permanence  and  the  least 
amount  of  fading  were  applied  in  combination  with  either  Sub- 
limed White  Lead  (Basic  Sulphate-White  Lead),  or  zinc  oxide, 
while  those  blues  which  were  applied  in  combination  with  Basic 
Carbonate-White  Lead  showed  marked  failure  and  were  com- 
pletely bleached  out,  due,  of  course,  to  the  alkaline  nature  of 
the  corroded  white  lead;  prussian  blues  being  transformed  by 
alkalies  to  a  white  compound. 

"  Superior  Value  of  Composite  Formulas.  Some  of  the  mixed 
leads,  or  so-called  graded  leads,  which  are  combinations  of  white 
leads  with  other  high-grade  pigments  and  containing  some  inert 
pigments,  were  not  deteriorated  so  far  as  the  white  lead  formulas, 
and  the  general  conclusion  was  that  they  were  upward  of  six 
months  behind  the  deterioration  of  the  straight  white  leads,  and 
this  was  confirmed  by  the  presence  of  moderate  chalking,  showing 
an  excellent  repainting  surface  and  a  better  thickness  and  condi- 
tion of  the  paint  coating. 

"  The  same  conclusions  which  were  reached  at  Atlantic  City, 
as  to  the  best  method  of  shellacking,  obtained  also  on  the  Pitts- 
burg  Fence,  namely,  that  application  of  the  shellac  to  the  wood 
previous  to  the  first  coat  is  the  better  method. 

"  Analysis  of  Paints.  At  the  time  of  the  painting  of  the  fence 
a  sample  of  each  paint  was  placed  in  small  friction  top  cans, 
carefully  labeled,  and  sent  to  the  Carnegie  Technical  Schools' 


RESULTS  OF  PITTSBURG  TESTS  143 

laboratory  for  analysis.  The  analyses  of  these  paints  were 
made  by  members  of  the  Test  Fence  Committee,  representing 
the  schools,  and  appear  in  this  bulletin.  The  results  obtained 
conform  very  closely  to  the  formulas  which  were  applied  to  the 
fence,  a  variance  of  only  one  or  two  per  cent,  being  shown  in 
the  amount  of  the  different  pigments." 

Second  Annual  Inspection  of  Pittsburg  Test  Fence.  The 
second  annual  inspection  of  the  Pittsburg  Test  Fence  was  made 
on  Thursday,  May  7th,  1910.  The  panels  in  Pittsburg  after 
having  weathered  for  over  two  years  presented  an  appearance 
which  allowed  the  making  of  a  detailed  inspection,  this  having 
been  found  impossible  during  the  first  annual  inspection.  The 
inspection  party l  included  those  master  painters  who  repre- 
sented the  Pittsburg  Master  Painters'  Association,  who  were  in 
charge  of  the  application  of  the  paints  in  1907,  1908,  and  1909, 
together  with  the  test  fence  committee  from  the  faculty  of 
the  Carnegie  Technical  Schools,  and  representatives  of  the 
Scientific  Section.  A  summary  of  the  report  issued  by  this 
committee  follows: 

"  Two  of  the  members  of  the  inspection  party  have  been 
impressed  with  the  lumber  lottery  existing  in  some  field  tests, 
which  have  been  conducted,  and  feel  that  when  the  object  'of  a 
test  is  to  determine  the  relative  value  of  paints,  such  tests  should 
be  conducted  on  a  standard  grade  of  wood,  such  as  white  pine. 
The  use  of  cypress,  pitch  pine,  and  other  faulty  woods,  is  often 
the  cause  of  the  failure  of  a  paint,  which  on  good  wood  would 
show  up  well.  For  this  reason,  only  the  white  pine  panels  painted 
with  white  paints  were  considered  in  the  inspection,  the  yellow 
pine  panels  and  cypress  panels  having  been  thrown  out  of  the 
test  at  last  year's  inspection. 

"  Checking,  cracking,  and  alligatoring  on  the  painted  surfaces 
were  determined  by  using  a  magnifying  glass.  The  degree  of 
chalking  existing  was  decided  upon  by  using  small  pieces  of  black 

*A.  C.  Rapp,  Chairman,  Test  Fence  Committee,  Pittsburg  Branch, 
Master  Painters'  Association;  John  Dewar,  member  Fence  Committee, 
Pittsburg  Branch,  Pennsylvania  State  Association  of  Master  Painters;  J. 
H.  James,  Chairman,  Carnegie  Technical  Schools'  Test  Fence  Committee; 
John  A.  Schaeffer,  member  Test  Fence  Committee,  Carnegie  Technical 
Schools;  Henry  A.  Gardner,  Director  Scientific  Section,  Paint  Manufacturers' 
Association  of  the  U.  S. 


144  PAINT  TECHNOLOGY  AND  TESTS 

felt  cloth,  rubbing  them  against  the  surface  of  the  panel;  the 
degree  of  whiteness  removed  upon  the  cloth  being  indicative  of 
the  amount  of  chalking  taking  place.  General  condition  was 
decided  upon  after  carefully  weighing  the  opinion  of  each  member 
of  the  inspection  party,  as  regards  the  general  characteristics 
shown  by  each  paint,  such  as  checking,  chalking,  scaling,  condi- 
tion for  repainting,  hiding  power,  etc.  The  results  have  been 
charted  and  presented  in  this  manner: 1 


Panel  on  Left  Painted  with  Single  Pigment  Paint;  Panel  on  Right 
Painted  with  Combination  Pigment  Paint.  Photograph  taken 
after  Two  Years'  Exposure  on  Pittsburg  Test  Fence 

"  Conclusions  Reached  from  the  Test.  The  primary  object 
of  the  test  made  at  Pittsburg  was  to  determine  whether  a  com- 
bination paint,  made  of  two  or  more  pigments,  would  be  equal 
or  superior  to  single  pigment  paints.  After  one  year's  exposure, 
the  combination  type  of  paint  proved  more  durable  than  the 
single  pigment  paints. 

"  It  was  early  apparent  that  the  combination  type  of  paints, 
that  is,  those  paints  made  of  more  than  one  pigment,  indicated 
in  most  cases  very  excellent  wear,  with  a  minimum  of  blackness 
and  a  general  good  condition  of  surface. 

"  Recommendation.  On  account  of  the  peculiar  conditions 
which  obtain  in  and  around  Pittsburg,  as  exemplified  by  these 
tests,  the  committee  finds,  as  a  result  thereof,  that  the  best  white 

1  An  endeavor  was  made  to  use  uniform  terms  in  reporting  on  each  for- 
mula. In  some  cases  it  was  necessary  to  bring  out  more  forcibly  the  con- 
dition by  the  insertion  of  qualifying  remarks. 


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RESULTS  OF  PITTSBURG  TESTS  147 

paint  for  general  exterior  use  is  made  of  white  lead  combined 
with  zinc  oxide  and  a  moderate  percentage  of  inert  pigments, 
such  as  silica,  asbestine,  or  barytes. 

"  Some  Peculiar  Conditions  Affecting  the  Tests.  The  in- 
spectors were  most  impressed  during  the  inspection  by  the 
blackness  exhibited  to  such  a  high  degree  by  certain  panels,  and 
the  fair  degree  of  whiteness  by  others.  It  is  well  known  that 
in  Pittsburg  nearly  all  paints  become  darkened  by  the  deposition 
on  their  surface  of  carbon  particles  emanating  from  the  com- 
bustion of  soft  coal.  Certain  of  the  paints,  however,  presented 
fairly  white  surfaces,  and  it  would  thus  appear  that  the  extreme 
darkness  shown  by  other  paints  was  due  to  their  composition. 
Corroded  white  lead  when  used  alone  was  uniformly  covered  by 
black  particles,  and  the  higher  the  percentage  of  corroded  white 
lead  in  a  paint  the  darker  was  the  surface.  It  was  at  first  thought 
that  this  darkness  was  due  to  the  softness  of  the  white  lead 
pigment  or  to  its  roughened  surface,  in  causing  adherence  of  soot 
particles.  Sublimed  white  lead,  however,  which  is  also  a  soft 
pigment,  chalked  even  more  progressively  than  corroded  white 
lead,  but  its  surface  was  not  rough,  and  presented  a  very  white 
appearance.  Scrapings  from  the  different  panels  are  being  taken, 
and  after  a  careful  analysis  the  findings  from  the  investigations 
will  be  reported  by  a  member  of  the  Inspection  Committee." 

A.  C.  RAPP.  Chairman  Test  Fence  Committee,  Pittsburg  Branch, 

Master  Painters'  Association 

JOHN  DEWAR.  Member  Fence  Committee,  Pittsburg  Branch,  Penna.  State 

Association  of  Master  Painters 

J.  H.  JAMES.  Chairman  Carnegie  Technical  Schools'  Fence  Committee 

J.  A.  SCHAEFFER.      Instructor  in  Chemical  Practice,  Carnegie  Technical  Schools 

Pittsburg,  Pa. 

H.  A.  GARDNER.        Director  Scientific  Section,  Paint  Mfrs.  Asso.  of  U.  S. 

May  31,  1910 


148 


PAINT  TECHNOLOGY  AND   TESTS 


PITTSBURG  TEST  FENCE 

COMPARATIVE  SPREADING  RATES  OF  WHITE  PAINT  ON  WHITE  PINE  PANELS 
Average  Spreading  Rate  266  Square  Feet 


Formula 
Number 

First  Coat 
(sq.  ft.) 

Second  Coat 

(sq.  feet) 

Third  Coat 

(sq.  ft.) 

Average 
Spreading  Rate 
(sq.  feet) 

Spreading  Rate 
3-Coat  Work 

(sq.  feet) 

1 

759 

1020 

768 

849 

283 

2 

694 

975 

1229 

966 

322 

3 

743 

873 

770 

795 

265 

4 

537 

987 

1019 

848 

283 

5 

509 

896 

886 

764 

255 

6 

765 

1045 

994 

935 

312 

7 

734 

922 

996 

884 

295 

8 

565 

862 

854 

760 

253 

9 

622 

926 

1160 

903 

301 

10 

610 

1013 

1070 

900 

300 

11 

651 

933 

1010 

865 

288 

12 

675 

1027 

623 

775 

258 

13 

663 

892 

981 

845 

282 

14 

498 

785 

807 

697 

232 

15 

688 

1000 

984 

891 

297 

16 

669 

880 

860 

803 

268 

17 

635 

982 

1077 

900 

300 

18 

636 

959 

1031 

875 

292 

19 

626 

1076 

1037 

913 

304 

20 

591 

1015 

929 

845 

282 

21 

595 

948 

910 

818 

273 

22 

617 

868 

810 

765 

255 

23 

549 

1002 

986 

846 

282 

24 

539 

918 

783 

747 

249 

25 

530 

929 

850 

770 

257 

26 

532 

916 

1011 

820 

273 

27 

520 

850 

656 

675 

225 

33 

600 

1340 

810 

917 

306 

34 

471 

743 

690 

635 

212 

35 

402 

598 

645 

548 

183 

36 

398 

668 

838 

635 

212 

37 

579 

653 

838 

690 

230 

38 

463 

615 

704 

594 

198 

39 

474 

954 

849 

759 

253 

40 

446 

815 

871 

711 

237 

45 

527 

841 

916 

761 

254 

46 

605 

740 

818 

721 

240 

47 

735 

961 

993 

896 

299 

CHAPTER  X 
A  LABORATORY  STUDY  OF  TEST  PANELS 

Panel  Sections  for  Laboratory  Test.  In  order  to  make  a 
laboratory  study  of  the  painted  panels  on  the  Atlantic  City 
and  Pittsburg  fences,  it  was  thought  advisable  to  remove  small 
sections  from  representative  areas  and  transfer  them  to  the 
laboratory  for  such  work.  The  fences  were  visited  by  the  offi- 
cial inspection  committees  soon  after  the  first  annual  inspection, 
and  the  panels  were  carefully  looked  over.  Upon  each  was 
marked  out  a  representative  portion,  care  being  exercised  to 
select  areas  where  previous  inspections  had  not  disturbed  the 
surface  of  the  film  in  any  manner.  The  inspectors  then  placed 
the  number  of  the  panel  upon  the  areas  which  had  been  marked 
off,  as  well  as  their  initials.  The  marked  sections  were  sawed 
out,  wrapped  in  tissue  paper,  and  then  transferred  to  the  labora- 
tory where  they  were  placed  upon  models  of  the  respective  fences 
from  which  they  had  been  removed.  The  illustration  shows 
the  model  test  fences  set  up  together.  It  is  very  apparent  that 
the  Pittsburg  panels  are  much  the  darker  in  color,  due  to  the 
soot,  and  in  some  cases  lead  sulphide  formed  upon  their  surfaces. 
This  difference  was  undoubtedly  due  to  the  atmospheric  con- 
ditions prevailing  where  the  tests  were  made.  One  would  be 
led  to  suppose  that  a  paint  film  exposed  to  an  atmosphere  such 
as  is  found  in  Pittsburg  would  show  deterioration  more  rapidly 
than  one  exposed  in  Atlantic  City.  In  all  the  tests  and  experi- 
ments, however,  the  Atlantic  City  panels  appeared  broken  down 
to  a  much  greater  extent;  though  it  is  true  that  the  Pittsburg 
panels  had  darkened  considerably  and  presented  a  rather  mot- 
tled appearance.  The  deposit  of  soot  on  the  Pittsburg  panel 
seemed  to  act  as  a  preservative  coating  for  the  film  beneath, 
and  prevented  marked  disintegration. 

Chalking  Test.  Small  strips  of  black  felt,  about  one  inch 
square,  were  firmly  attached  to  a  block  of  wood,  and  by  a  clamp 
having  the  same  pressure  in  each  case,  the  wood  with  its  surface 

149 


150 


PAINT  TECHNOLOGY  AND  TESTS 


Sections  of  Atlantic  City  and  Pittsburg  Fences  Arranged  for  Laboratory 

Examination 


Sections  of  Atlantic  City  and  Pittsburg  Fences 


LABORATORY  STUDY  OF   TEST  PANELS  151 


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36-10 


31-10 


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Upper  set  of  tests  made  on  Panels  from  Atlantic  City  Fence 
Lower  set  of  tests  made  on  Panels  from  Pittsburg  Fence 
Figures  at  left  indicate  Formula  Number 
Figures  at  right  indicate  Degree  of  Chalking 


Color  Standard  used  in  Comparison  of  Panel  Section 


LABORATORY  SfUDY  OF  TEST  PANELS  153 

of  black  felt  was  fixed  to  the  panel.  This  apparatus,  which 
resembles  a  blackboard  eraser,  is  firmly  drawn  across  the  panel 
in  one  direction  for  a  certain  definite  distance,  during  which  time 
it  gathers  all  the  chalked  surface  presented  by  the  painted  wood. 
Upon  detaching  the  apparatus  from  the  panel  it  is  observed 
that  the  black  cloth  becomes  whitened  to  an  extent  proportionate 
to  the  chalking  that  has  taken  place  on  the  given  area. 

After  each  one  of  the  panels  had  been  treated  in  the  same  man- 
ner by  the  same  operator,  the  black  cloths  were  assembled  on 
one  large  board  and  photographed.  A  definite  standard  of 
chalking  was  made  up,  and  the  operator  was  enabled  to  put 
down  opposite  the  report  on  each  panel  the  degree  of  chalking 
which  had  taken  place,  No.  1  representing  the  least  amount  and 
No.  10  the  greatest  amount  of  chalking. 

Degree  of  Whiteness  Shown  by  Panels.  It  was  a  very  simple 
matter  to  gauge  the  w^hiteness  of  the  various  panels,  by  compar- 
ing them  with  a  series  of  standard  boards  painted  with  three 
coats  of  white  paint.  Florence  Brand,  New  Jersey  zinc  oxide, 
was  used  as  the  standard  for  whiteness  and  termed  "  No.  1.? 
In  making  "  No.  2  "  standard,  to  the  zinc  oxide  was  added  .01% 
of  lampblack.  By  adding  .02%  of  lampblack  to  the  zinc, 
standard  "  No.  3  "  was  obtained,  and  so  on,  increasing  the 
amount  of  lampblack  in  each  case  by  .01%.  These  standards 
were  run  up  to  "  No.  30,"  and  the  various  panels  on  the  different 
fences  compared  with  them.  The  degrees  of  whiteness  are 
recorded  in  progressive  numbers,  No.  1  being  the  standard  for 
whiteness  and  No.  30  the  darkest.  The  Atlantic  City  panels 
ranged  from  3  to  8  in  the  scale  of  whiteness,  while  the  Pittsburg 
panels  required  the  use  of  the  entire  range  of  standards. 

Resistance  to  Abrasion.  The  apparatus  used  for  determining 
the  abrasion  resistance  of  a  paint  was  made  of  a  glass  tube  about 
six  feet  long,  having  an  internal  bore  of  f  inch.  This  was 
supported  in  an  upright  position  over  a  dish  which  held  the  panel 
under  test  at  an  angle  of  45  degrees.  The  abrasive  material 
consisted  of  No.  00  emery,  which  was  dropped  into  the  tube 
through  a  funnel  having  a  bore  of  5  mm.  When  the  emery 
reached  the  bottom  of  the  long  tube  it  scattered  itself  so  as  to 
strike  a  surface  on  the  panel  about  an  inch  in  diameter.  The 
emery  was  constantly  poured  in  until  the  paint  coating  had  worn 
away,  showing  the  bare  wood.  The  weight  in  pounds  of  emery 


Apparatus  for  Determining  the  Abrasion  Resistance 
of  Paints  154 


LABORATORY  STUDY  OF  TEST  PANELS  155 


Formula  No.  1,  A.  C. 


Formula  Xo.  3,  A.  C. 


156 


PAINT  TECHNOLOGY  AND  TESTS 


Formula  No.  4,  A.  C. 


Formula  No.  6,  A.  C. 


NOTE:  The  author  wishes  to  ac- 
knowledge the  assistance  of  Dr.  J.  A. 
Schaeffer  in  the  preparation  of  the 
photomicrographs  herewith  shown. 


LABORATORY  STUDY  OF  TEST  PANELS  157 


Formula  No.  7,  A.  C. 


Formula  No.  9,  A.  C. 


158  PAINT  TECHNOLOGY  AND  TESTS 


Formula  No.  10,  A.  C. 


Formula  No.  12.  A.  C. 


LABORATORY  STUDY  OF  TEST  PANELS  159 


Formula  No.  13,  A.  C. 


Formula  Xo.  15,  A.  C. 


160  PAINT   TECHNOLOGY  AND   TESTS 


Formula  No.  16,  A.  C. 


Formula  No.  18,  A.  C. 


LABORATORY  STUDY  OF  TEST  PANELS  161 


Formula  No.  19,  A.  C. 


Formula  No.  33,  A.C. 


162 


PAINT   TECHNOLOGY  AND   TESTS 


Formula  No.  34,  A.  C. 


Formula  No.  36,  A.  C. 


LABORATORY  STUDY  OF  TEST  PANELS  163 


Formula  No.  37,  A.  C. 


Formula  No.  39,  A.  C. 


164 


PAINT   TECHNOLOGY  AND   TESTS 


Formula  No.  40,  A.  C. 


Formula  No.  46,  A.  C. 


LABORATORY  STUDY  OF  TEST  PANELS  165 

powder  required  to  show  the  disruption  of  the  coating  is  recorded 
and  reported  as  the  measure  of  the  "  abrasion  resist."  The 
panel  requiring  the  greatest  weight  of  emery  to  cause  abrasion 
is  evidently  the  most  resistant  to  abrasion.  Paint  is  often  sub- 
jected to  serious  abrasion,  through  the  blowing  of  sand,  especially 
at  the  seashore,  and  to  withstand  such  action  should  contain 
a  proportion  of  pigments  especially  resistant  to  abrasion,  such 
as  silica,  zinc  oxide,  asbestine,  and  barytes. 

Making    Photomicrographs.     The    photomicrographs    which 
are  herewith  shown  were  made  in  the  following  manner:    A 


Formula  No.  47,  A.  C. 

part  of  a  panel  was  placed  upon  the  stage  of  the  microscope  and 
held  firmly  in  place  with  clips.  By  varying  the  adjustment 
and  carefully  running  over  the  field  the  condition  of  the  surface 
was  readily  given,  using  the  same  eye-piece  and  objective  through- 
out the  tests,  and  obtaining  a  magnification  of  thirty-three. 
Great  care  was  exercised  to  secure  an  average  field  showing  the 
general  and  typical  appearance  of  every  panel.  Little  difficulty 
was  experienced  in  so  doing,  as  the  laboratory  panels  gave  very 
representative  surfaces  of  the  large  panels  on  the  fence.  The 
instrument  was  then  inclined  horizontally  and  the  eye-piece 
was  fitted  into  the  camera  nose.  In  the  back  of  the  bellows  of 
the  camera  was  placed  the  ground  glass  for  focusing.  To  secure 


166  PAINT  TECHNOLOGY  AND   TESTS 

illumination  the  light  from  an  electric  arc  lamp  was  reflected 
from  a  mirror  directly  upon  the  painted  surface  of  the  panel, 
which  in  turn  was  reflected  through  the  camera  on  to  the  ground 
glass.  The  plate-holder  was  then  put  in  position  and  six-second 
exposures  were  made,  afterward  developing  and  printing. 

Checking  and  Cracking.  What  was  termed  "  fine  matt 
checking  "  at  the  First  Annual  Inspection  was  not  visible  at 
the  time  to  certain  members  of  the  Inspection  Committee,  but 
it  is  an  established  fact  that  the  checking  was  an  existing  con- 
dition, as  the  photomicrographs  have  shown.  This  checking 
has  a  very  peculiar  characteristic  in  that  the  lines  are  very  narrow 
and  hair-like,  being  somewhat  interlaced  and  peculiarly  forked. 
That  this  hair  matt>  checking  is  a  preliminary  condition  which 
afterwards  develops  into  matt  checking  and  into  marked  or  heavy 
checking  seems  to  be  indicated. 

It  appears  from  an  examination  of  the  photomicrographs  of 
the  paint  films  that  a  paint  coating  closely  resembles  the  surface 
of  the  earth,  and  is  subject  to  the  same  basic  laws  that  have 
caused  the  various  geodetic  changes  in  the  earth's  crust.  Ob- 
servation of  a  dried  pond  or  lake  bed  will  disclose  types  of  fissur- 
ing  and  cracking  similar  to  those  shown  by  dried  paint  coatings 
in  which  the  oil  has  been  fully  oxidized,  and  especially  in  the 
case  of  paints  containing  pigments  which  act  upon  the  oil  to 
produce  compounds  brittle  in  nature. 

At  Atlantic  City  the  panels  were  all  clean  and  free  from  dirt, 
presenting  continuous  exposure  of  the  films,  and  thus  main- 
taining conditions  for  active  checking.  At  Pittsburg,  soon  after 
the  panels  began  to  chalk,  the  large  amount  of  dust  and  black 
soot  in  the  atmosphere  completely  covered  the  panels  with  a 
very  thick,  resistant  coating  of  carbon,  which  acted  as  a  seal 
or  protector,  preventing  disintegration  to  a  great  extent.  This 
coating  was  extremely  hard  to  remove,  and  photomicrographs, 
before  and  after  removal  of  this  coating  by  rubbing  with  a  damp 
cloth,  failed  to  reveal  marked  checking  on  any  of  the  formulas 
except  those  made  of  strictly  pure  basic  carbonate-white  lead. 
The  checking,  even  on  these,  was  not  as  marked  as  at  Atlantic 
City.  It  is  presumed  that  after  the  chalking  had  taken  place 
and  the  chalked  pigment  had  been  washed  from  the  panels,  the 
gradually  increasing  coat  of  carbon  and  lead  sulphide  had  pro- 
tected the  panels  from  checking,  or  possibly  the  atmosphere  of 


LABORATORY  STUDY  OF  TEST  PANELS 


167 


Combination  Formula 
No.  1,  Pittsburg 

BEFORE  WASHING 

Mottled  surface  due 
to  external  coating  of 
impurities. 


AFTER  WASHING 


168 


PAINT  TECHNOLOGY  AND   TESTS 


Formula  No.  4,  Pittsburg 
BEFORE  WASHING 


AFTER    WASHING 


LABORATORY  STUDY  OF   TEST  PANELS 


169 


Formula  No.  38, 
Pittsburg 

Basic  Carbonate  — 
White  Lead  Panels 
on  Fence 

BEFORE  WASHING 
Checking   evident 
even  through  the  outer 
covering   of    foreign 
matter. 


AFTER  WASHING 


170 


PAINT   TECHNOLOGY  AND   TESTS 


Formula  No.  36, 

Pittsburg 

Basic  Carbonate  — 
White  Lead  Panels 
on  Fence 

BEFORE  WASHING 
Peculiar     network- 
like  checking  appear- 
ing through  outer  coat 
of  impurities. 


AFTER  WASHING 


LABORATORY  STUDY  OF   TEST  PANELS  171 


Formula  No.  40, 
Pittsburg 


Formula  No.  45, 
Pittsburg 


172         PAINT  TECHNOLOGY  AND  TESTS 

Pittsburg,  which  in  other  respects  had  deteriorated  the  panels 
to  a  greater  extent  than  at  Atlantic  City,  did  not  have  the  extreme 
action  in  causing  checking  that  the  Atlantic  City  atmosphere 
seemed  to  have  effected. 

Results  on  Combination  Pigment  Paints.  It  will  be  noticed 
that  the  checking  on  most  of  the  combination  pigment  paints 
made  of  lead,  zinc,  and  inert  pigments,  was  moderate,  and  in 
many  cases  of  a  fine  order.  It  has  been  observed  that  the 
percentage  of  zinc  oxide  in  a  paint  is  not  always  a  criterion  upon 
which  future  checking  may  be  judged.  Nor  could  it  be  said 
that  the  checking  is  dependent  upon  the  percentage  of  basic 
carbonate-white  lead  added  to  the  paint.  However,  it  appears 
that  scientific  blending  of  the  various  pigments,  with  regard  to 
their  physical  properties  in  oil,  such  as  their  strength  and  elastic 
limit,  develops  the  greatest  resistance  to  both  cracking  and 
checking.  Elasticity  is  vital,  but  strength  must  be  combined 
therewith  in  order  to  prevent  disruptions  of  the  paint  coating. 
Paint  films  made  of  certain  inert  pigments,  when  tested  on  the 
filmometer,  were  relatively  high  in  strength,  but  relatively  low 
in  elasticity.  Such  pigments,  when  used  in  large  percentage, 
form  coatings  which  are  hard  and  apt  to  crack.  The  use,  how- 
ever, of  these  pigments  in  moderate  percentages  seems  very 
beneficial  in  overcoming  the  effect  of  using  an  excessive  per- 
centage of  white  lead,  or  of  zinc  oxide. 

Results  on  White  Lead  Paints.  The  maximum  checking 
was  observed  on  the  basic  carbonate-white  lead  panels,  the  size 
of  the  checks  in  some  cases  being  several  times  larger  than  those 
on  the  other  panels. 

On  some  of  the  basic  carbonate-white  leads  the  checking  was 
of  a  very  peculiar  nature,  consisting  of  very  broad  fissures  in 
the  paint  coating,  disclosing  the  wood  surfaces  beneath.  The 
type  of  checking  existing  was  also  distinct  in  its  structure,  being 
hexagonal  in  shape.  One  of  the  most  marked  features  shown 
by  the  basic  carbonate-white  lead  films  was  the  extreme  rough- 
ness of  their  surfaces.  This  roughness  is  most  likely  due  to  the 
excessive  chalking  which  had  taken  place. 

Results  on  Silica  and  Barytes  Paints.  The  checking  of 
paints  very  high  in  silica  resolved  itself  into  fine  hair-like  lines 
which  are  generally  lateral  to  each  other,  and  indicate  a  cracked 
appearance.  The  checking  of  paints  containing  very  high  per- 


LABORATORY  STUDY  OF  TEST  PANELS  173 

centages  of  barytes  was  also  of  a  distinct  nature,  being  generally 
forked  in  appearance  and  of  no  definite  striation. 

Surface  Condition  of  Fume  Pigment  Paints.  The  panels 
painted  with  basic  sulphate-white  lead  (sublimed  white  lead) 
showed  complete  absence  of  checking.  This  was  also  true  of 
the  panels  painted  with  zinc  lead.  These  are  both  fume  prod- 
ucts and  are  extremely  fine  in  their  physical  size,  which  may 
account  for  this  condition.  Although  zinc  oxide  is  made  in  a 
similar  manner,  it  gives  a  much  harder  paint  coating  than  either 
of  the  afore-mentioned  pigments,  and  presents  a  surface  which 
develops  considerable  checking,  generally  of  a  medium  order. 
The  past  theories  regarding  zinc  oxide,  in  which  it  has  been  main- 
tained that  zinc  oxide  gives  the  maximum  checking,  are  evidently 
incorrect,  as  the  checking  found  on  the  zinc  oxide  panels  was 
not  as  marked  or  deep  as  the  checking  on  the  basic  carbonate- 
white  lead  panels;  in  fact,  the  checking  might  be  more  in  the 
line  of  a  cracking,  possibly  due  to  the  brittle  nature  of  the  coating 
composed  of  straight  zinc.  This  is  especially  true  of  zinc  paints 
containing  insufficient  oil. 

The  Importance  of  the  Physical  Nature  of  Pigments.  It 
appears  that  very  fine  grinding  of  materials,  chosen  for  their 
characteristic  fineness,  with  the  absence  of  any  unfavorable 
physical  condition  or  chemical  sensitiveness,  are  important 
factors  in  the  making  of  a  paint  to  resist  cracking  or  checking. 
The  purity  of  the  essential  materials,  as  well  as  the  scientific 
compounding  of  these  materials,  with  due  regard  to  the  law  of 
minimum  voids,  are  great  factors  which  enhance  the  qualities 
of  paints,  greater,  perhaps,  than  the  variation  of  percentages  of 
the  various  pigments  which  go  to  make  up  a  paint. 


CHAPTER  XI 
ADDITIONAL  TESTS  AT  ATLANTIC   CITY  AND  PITTSBURG 

A  SERIES  of  new  test  panels  to  take  the  place  of  those  panels 
which  were  condemned  and  subsequently  removed  from  the 
Atlantic  City  and  Pittsburg  fences,  were  painted  and  exposed 
during  June,  1909.  These  new  test  panels  are  of  white  pine, 
this  wood  having  been  selected  by  the  joint  inspection  com- 
mittee as  offering  the  best  condition  for  future  tests.  The 
method  used  in  painting  these  panels  was  the  same  as  in  the 
previous  tests,  together  with  the  adoption  of  certain  refinements 
in  the  reductions,  application,  etc.  Thirty-six  formulas  were 
selected  with  careful  regard  to  the  percentage  of  components, 
including  several  paints  containing  lithopone  combined  with 
whiting  and  zinc  oxide,1  two  pigments  which  gave  promise  of 
supporting  the  lithopone  for  outside  use.  Some  of  these  litho- 
pone paints  contained  special  vehicles  which  it  was  thought 
would  prevent  the  destructive  action  which  lithopone  seems  to 
have  upon  linseed  oil.  In  order  to  obtain  a  criterion  of  the 
value  of  the  new  formulas  applied,  as  against  the  wearing  of 

1  A  brief  study  of  the  theory  of  solutions  (See  Cushman  and  Gardner  on 
"Corrosion  and  Preservation  of  Iron  and  Steel"),  involving  the  modes  of 
iron  formation,  will  be  invaluable  to  the  student  who  is  inquiring  into  the 
cause  of  the  peculiar  fogging  of  lithopone,  with  the  idea  in  view  of  correcting 
this  evil  by  physical  or  chemical  treatment.  Inasmuch  as  our  observations 
thus  far  have  led  us  to  believe  that  the  fogging  of  lithopone  takes  place  in  the 
presence  of  moisture,  with  the  contributory  and  necessary  action  of  chemi- 
cally active  rays  from  the  sun  or  other  source,  it  is  fair  to  assume  that  under 
these  conditions  the  insoluble  molecule  of  zinc  sulphide  and  barium  sulphate 
reverts  by  intricate  molecular  disturbance  and  ionization  back  to  the  soluble 
barium  sulphide  and  zinc  sulphate  from  which  the  lithopone  is  formed  by 
metathesis.  If  this  be  true,  then  the  acid  nature  of  these  soluble  salts  is  no 
doubt  combated  and  overcome  at  the  moment  of  formation  by  the  basic 
nature  of  zinc  oxide  and  calcium  carbonate,  which  tend  to  ionize  to  an 
alkaline  reaction.  The  value  of  zinc  oxide  and  calcium  carbonate  in  litho- 
pone paints  as  detergents  of  blackness,  has  been  demonstrated  at  both 
Atlantic  City  and  Pittsburg."  H.  A.  G. 

174 


GO 


176  PAINT  TECHNOLOGY  AND   TESTS 


Appearance  of  1909  Tests 


TESTS   AT   ATLANTIC   CITY   AND    PITTSBURG         177 

straight  white  leads,  the  original  white  leads  used  in  the  previous 
tests  were  included,  and  other  brands  were  added.  Each  formula 
was  painted  out  in  white,  yellow,  and  gray,  upon  panels  of  white 
pine  wood  arranged  in  sequence  upon  the  fence,  and  properly 
identified.  The  customary  opacity  test,  in  the  form  of  a  small 
black  square,  was  stencilled  over  the  priming  coat  of  each  panel, 
as  in  the  former  tests.  The  composition  of  the  vehicle  in  all 
the  new  tests  was  standard,  using  pure  linseed  oil  with  a  small 
percentage  of  turpentine  drier.  The  tints  used  in  each  formula 
were  secured  at  the  time  of  application  by  the  use  of  standard 
colors,  lampblack,  and  medium  chrome  yellow,  using  an  approxi- 
mate amount  for  each  formula. 

An  inspection  of  these  new  tests  was  made  during  June,  1910, 
and  the  results  of  the  inspection  are  shown  on  pages  174  to  177. 
The  results  of  the  inspection  prove  that  it  is  unsafe  to  use  litho- 
pone  in  a  paint  containing  white  lead  of  any  type,  early  darkening 
and  failure  being  shown  in  every  case  where  such  a  combination 
existed.  The  formulas  in  the  new  test,  which  were  properly 
balanced  and  which  had  a  low  percentage  of  lithopone  combined 
with  zinc  oxide  and  whiting,  presented  in  some  cases  very  good 
surfaces.  A  rough,  sandy  surface,  however,  was  shown  where 
lithopone  was  used  in  any  great  quantity. 


178 


PAINT  TECHNOLOGY  AND  TESTS 


TESTS   INAU 
RESULTS   OF    INSPECTION    OF   AT 


FORMULAS 

INERT  PIGMENTS 

REPORT  OF 
INSPECTION 

c3 

0> 

a 

3 

+9 

11 

"d 

w 

.2 

ta 

1 

o 

X 

Formula 
Number 

1 

Zinc  Oxii 

O}1"5 

Precipita 
White  L« 

Zinc  Lea 

1 
13 

Calcium 
Carbona 

o 

1 

a 

China  Cl 

1 

E 

O       I 

CHALKING 

% 

% 

45 

% 

% 

40 

15 

% 

% 

% 

% 

% 

None 

2 





45 





40 

15 

— 







None    

3 

45 

_ 

_ 

45 

10 

_ 



_ 

_ 

_ 

Very  slight    .  . 

4 

— 

45 

— 

— 

45 

10 

— 

— 

— 

— 

— 

None    

5 

_ 

40 

_ 

_ 



40 

20 







_ 



Very  slight    .  . 

6 



45 





35 



20 





. 

None    

7 

50 





36 





2 

8 

4 



None    

8 



50 



36 





2 

8 

4 



Heavy  

9 





50 



__ 

36 



. 

2 

12 



Heavy  

10 



36 

50 









2 

8 

4 



None    

11 

28 

55 









— 

3 

7 

7 

None    

12 

55 

28 











3 



"7 

7 

None    

13 

— 

60 

— 

— 

30 

10 

— 

— 

— 

Very  slight    .  . 

14 

— 

30 

30 

— 

— 

30 

10 

— 

— 

— 

— 

— 

Very  slight    .  . 

15 

_ 

60 

_ 

_ 

30 

_ 

_ 

10 

_ 

_ 

_ 

Heavy  

16 
17 

— 

— 

— 

— 

100 
100 

— 

— 

— 

— 

— 

Heavy    
Considerable  . 

18 
19 

33 
34 

33 
33 

— 

— 

— 

— 

— 

17 
33 

— 

17 

— 

— 

Very  slight    .  . 
Very  slight    .  . 

20 

34 

1  1  nn 

33 

— 

— 

— 

— 

— 

— 

— 

33 

— 

— 

Very  slight    .  . 
Slight 

21 
22 

OQ 

lUu 
100 
i  nn 

Very  slight    .  . 
Alodium 

£16 

24 
25 

lUu 

— 

100 

— 

100 

— 

— 

— 

— 

— 

— 

— 

Slight  ...'.". 
Medium  

26 

— 

— 

— 

100 

— 

— 

— 

— 

— 

— 

— 

Heavy  

27 

100 
i  nn 

,  ,e^.  y  

28 
29 

1UU 
24 

45 

13 

18 

Slight  

30 

45 

— 



— 

40 

15 

— 

— 

— 

— 

— 

Heavy  

31 

45 

_ 

_ 





40 



15 









None    

32 
33 

45 
50 

— 

— 

— 

— 

35 
36 

— 

— 

20 
2 

— 

12 

— 

Slight  
Considerable  .  . 

34 

75 



25 









— 

— 

— 

— 

— 

None    

35 

50 



50 



















None    

36 

— 

— 

— 

— 

— 

100 

— 

— 

— 

— 

Extremely  bad 

1  This  pigment  on  analysis  proved  to  be  zinc  lead. 


TESTS   AT   ATLANTIC   CITY  AND   PITTSBURG 


179 


GURATED  IN   1909 

LANTIC    CITY  TEST   FENCE,    MAY,    1910 


REPORT   OF   INSPECTION 


CHECKING 

GENERAL   CONDITION 

REMARKS 

None    

Rough    surface,   but    fair    for 

repainting  

None                            

Fair  ;  rough  surface  and  slightly 

dark  

Very  slight      . 

Good;  very  white  surface  .... 

Rough    surface    and    slightly 

dark     

Very  slight                       

Good;  very  white  surface  .... 

None          

Rough  surface;  dark  .  . 

Very  slight  lateral  checking   .  . 

Good    

Slight  

Excellent  ;  very  white  

Some                         

Excellent;  very  white  .  . 

Slight 

Good    

Slight                  

Good;  slightly  dark  .  . 

Slight  lateral 

Good    ......  

Considerable    lateral   running 
along  grain  of  wood 

Fair    . 

Considerable    lateral   running 
along  grain  of  wood 

Fair    . 

Fair 

Considerable    

Dark  color;  rough  surface.  .  .  . 

Medium    

Better   than    No.    16;    not    as 

rough  or  dark  

None 

Good 

Slight 

Good    . 

Good 

Slight 

Fairly  good 

Lateral  cracking 

Fair    

Good  for  repainting 

Slight  cracking  

Fair;  surface  rough  &  dark.  .  . 
Fair 

Considerable   

Poor;    very   rough,   dark  sur- 

face 

None 

Good    

Heavy   checking   and   alliga- 
toring    

Poor 

Med  '&      mg  

Slight 

Poor  ;  dark  surface  

None 

Fair*  dark  surface  

Slight 

Fair*  rough  surface 

Fair      '.  

Vehicle     disintegrated; 

spotted  in  places  

180 


PAINT  TECHNOLOGY  AND   TESTS 


TESTS   INAUGU 
RESULTS   OF    INSPECTION    OF   PITTS 


FORMULAS 

REPORT  OF 
INSPECTION 

Si      tH 

a  2 
II 

£2; 

2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 

17 

18 
19 
20 
21 
22 
23 
24 
25 
26 

27 

28 

29 
30 
31 
32 
33 
34 
35 
36 

Basic  Carbonate 
White  Lead 

Zinc  Oxide 

Basic  Sulphate 
White  Lead 

1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  ,q  1  Precipitated 
|  White  Lead 

Zinc  Lead 

Lithopone 

Inert  Pigment 

Calcium 
Carbonate 

S3 

£ 

OQ 

Asbestine 

China  Clay 

» 

1 

& 

« 

% 

4 
4 
12 
4 

7 

7 

8 

S 

o 

c 

3 

Chalking 

% 

50 

28 

% 

45 
40 

36 
55 
55 
60 
30 

% 

45 
45 

45 
45 

50 
50 
50 

28 

30 
60 

% 
36 

% 

40 
40 
45 
45 
40 
35 

36 
36 

30 
30 
30 

% 
15 

10 
10 
20 

10 
10 

% 

15 

% 

20 
2 
2 
2 
2 
3 
3 

10 

% 

8 

8 

8 

% 

7 
7 

Considerable  .  .  . 

Slight  
Medium  . 

Considerable  .  . 
Slight  
Medium 

Medium  
Extremely  bad 

Extremely  bad   .  . 
Slight  .  .  . 

Slight  
Medium  
Medium 

Heavy  
Extremely  bad  
Extremely  bad  

Not  as  bad  as  No.  16... 

Very  slight  
Very  slight  
None  
Slight  
Medium  
Slight  
Bad  
Slight  
Medium  

Medium  
Medium  

Slight 

33 
34 
34 
100 
ilOO 
100 

100 
100 

24 
45 
45 
45 
50 
75 
50 

33 
33 
33 

— 

— 

— 

100 

— 

17 
33 

— 

17 
33 

— 

— 

— 

100 

100 

100 

— 

— 

— 

— 

— 

— 

— 

45 

13 

25 
50 

— 

— 

40 
40 
35 
36 

15 

15 

100 

18 

20 
2 

— 

12 

— 

None  
Very  slight  
Extremely  slight  
Extremely  slight  
Slight  
Considerable  
Extremely  bad  

1  This  pigment  on  analysis  proved  to  be  zinc  lead. 


TESTS   AT   ATLANTIC    CITY   AND    PITTSBURG 


181 


RATED   IN   1909 

BURG   TEST   FENCE,   MAY,    1910 


REPORT  OF  INSPECTION 


Checking 

General 
Condition 

Remarks 

s 

Slight  .. 

Fair  

Dark  in  places.     Diffused    

1 

Bad                                         

Fair 

Dark  in  places  ...    . 

2 

None  .  . 

Good  .  . 

Darkening  shown  in  places   

3 

None  
None 

Good  
Good 

Medium  dark  
No  excessive  darkness 

\ 

Slight    
None  

Good  
Excellent  

Surface  fairly  white    
Whitest  surface  of  new  tests  

6 

7 

Slight    . 

Fair  

Surface  darkening  

g 

Slight    
None 

Fair  
Good 

Not  as  bad  as  No.  8  
Excellent  surface;  very  white 

9 
10 

None  
None 

Excellent  
Good 

Surface  fairly  white;  thin  soot  
Surface  white  . 

11 

12 

Very  bad  in  spots   

Fair  

Slight  darkening  

13 

Considerable    

Fair  . 

Slight  darkening  ...    . 

14 

Slight 

Fair 

Fairly  white 

15 

Advanced  and  deep    

Less  advanced  than  No.  16.  ... 
Practically  none                       .  . 

Bad  

Fair    
Fair 

Surface      rough      with      considerable 
disintegration     and     much     dark- 
ness    
Not    as    dark    as    No.     16;    slightly 
mottled  in  places;  buff  color  
Surface  white  .  . 

16 

17 
18 

None 

Good 

Surface  fairlv  white 

19 

None  
Slight 

Good  
Fair 

Surface  fairly  white    
Surface  very  rough  and  dark 

20 
21 

Slight    
Bad  
None 

Fair  
Fair  
Good 

Surface  fairly  white  
Surface  rough  and  darkest  on  fence  .  .  . 
Surface  white 

22 
23 
24 

None  
Slight 

Good  
Fair 

Fairly  white  surface   
Rough    and   very    dark'    chalking   is 

25 

Slight 

Good 

disrupting  black  coating    
Surface  fairly  white 

26 
27 

Deep;     evident      without 
glass 

Poor 

Surface  rough  and  very  dark  .  . 

28 

Slight 

Good 

29 

Slight    
Advanced 

Fair  
Fair 

Color  dark  
Color  very  dark 

30 
31 

Considerable    
Slight    . 

Fair  
Fair 

Color  very  dark;  rough  surface    
Surface  dark  and  rough  .  .        

32 
33 

Deep 

Fair 

34 

Slight    . 

Fair  .          ... 

Surface  medium  dark  

35 

None 

Fair 

Vehicle     disintegrated,    leaving    very 

white,     chalked     surface     of      pig- 
ment      

36 

CHAPTER   XII 
NORTH  DAKOTA  PAINT  TESTS 

AN  inspection  of  the  original  test  fence,  erected  and  painted 
by  the  North  Dakota  Agricultural  College,  on  the  grounds  of 
the  agricultural  Experiment  Station  at  Fargo,  was  made  by  the 
inspection  committee *  representing  the  Paint  Manufacturers' 
Association  of  the  United  States,  on  the  19th  and  20th  of  Novem- 
ber, 1909.  The  fence  was  erected  in  1906  and  painted  with 
commercial  paints,  procured  in  the  open  market.  The  east  side 
of  the  fence  was  built  of  soft  pine  and  cedar  weather-boarding, 
such  as  is  almost  universally  used  on  houses  in  that  locality, 
presenting  a  very  good  surface  for  test  purposes,  while  the  west 
side  was  built  largely  of  flat  trimmed  boards  of  hard  pitch  pine 
which,  unfortunately,  contained  knots,  pitch  pockets,  and  uneven 
surfaces,  causing  to  a  greater  or  lesser  extent  cracking,  scaling, 
and  bad  general  results  on  all  paints  applied  thereto. 

The  fences  built  in  1907  and  1908  at  the  suggestion  of  the  Paint 
Manufacturers'  Association,  were  inspected  on  the  20th,  21st, 
and  22nd  of  November,  1909,  and  the  detailed  results  of  the 
inspection  of  all  these  fences  follow  in  this  report.  The  same 
general  conclusions  as  to  the  woods  represented  in  the  1906 
fence  also  apply  to  the  1907  and  1908  fences,  and  because  of 
the  general  bad  quality  of  wood  used  on  the  western  exposure 
of  all  fences,  the  detailed  reports  were  made  only  from  an  ex- 
amination of  the  eastern  side  of  the  fences,  both  on  cedar  and 
soft  pine. 

The  following  general  summary  of  the  inspection  and  its  re- 
sults applies  to  all  the  test  fences  on  the  grounds  of  the  college 
and  is  the  unanimous  conclusion  drawn  by  the  inspectors  from 
this  work: 

"  Non-absorbent  woods,  difficult  to  penetrate,  such  as  those 
on  the  west  side  of  the  fences,  would  undoubtedly  have  given 

1  Henry  A.  Gardner,  Director  Scientific  Section,  Educational  Bureau, 
Paint  Manufacturers'  Association  of  U.  S.;  George  Butler,  Master  Painter; 
Charles  MacNichol,  Master  Painter. 

182 


NORTH  DAKOTA  PAINT  TESTS 


183 


North  Dakota  Test  Fences 


Typical  Sample  of  Hard  Pine  Trim  Board  Showing  Knot  and  Sappy  Grain 


184 


PAINT  TECHNOLOGY  AND  TESTS 


Test  No.  13  —  1906  Fence 
Complete  Disintegration  and  Failure  of  Cheap  Paint 


NORTH   DAKOTA    PAINT    TESTS  185 

much  better  results  had  they  been  painted  with  paints  properly 
reduced  to  suit  the  nature  of  the  wood.  This  treatment  seems 
to  have  been  overlooked  in  the  North  Dakota  tests,  and  the 
painting  of  the  hard  pine  boards  was  done  with  the  same  con- 
sistency of  mixtures  and  the  same  reductions  as  upon  soft  pine. 
Scaling  of  course  resulted.  One  of  the  chief  purposes  of  the 
fences,  however,  was  to  study  the  different  types  of  wood,  and 
compliance  with  this  desire  resulted  in  the  bad  conditions  herein 
noted.  It  has  been  shown  in  many  other  field  tests  that  adher- 
ence of  paints  to  hard  wood  surfaces  can  be  obtained  only  by 


Pine  Weather-boarding  Showing  Knots  and  Grain 

causing  the  priming  coat  to  become  amalgamated  with  the 
woody  fibre,  by  the  use  of  a  large  percentage  of  volatile  diluent 
turpentine,  benzole,  asphaltum  spirits^  etc.,  to  secure  penetra- 
tion. If  such  treatment  is  omitted,  failure  soon  results,  as  was 
evidenced  by  the  uniformly  bad  conditions  presented  by  the 
paints  on  the  hard  pine  panels. 

"  During  July,  1908,  a  violent  hailstorm  occurred  in  Fargo, 
and  left  its  impression  on  nearly  every  wooden  structure;  in 
many  cases  deep  dents  being  made  into  the  wood.  The  west 
side  of  the  test  fences,  which  received  the  most  injury  from  this 
storm,  was  covered  with  these  dents  over  almost  its  entire  surface, 
causing  cracks  in  the  form  of  concentric  rings  to  appear  on  the 


186 


PAINT  TECHNOLOGY  AND   TESTS 


abraded  paint  coatings.     The  bad  condition  of  the  wood,  im- 
proper method  of  applying  priming  coat,  combined  with  the 


_ 


Condition  of  Lumber  Affecting  Paint,  West  Side  1906  Fence 

hailstorm  effect  on  the  painted  surfaces  on  the  west  side  of  the 
fences,  were  undoubtedly  responsible  for  the  universal  failure 
of  the  paints  thereon,  and,  for  these  reasons,  the  west  side  was 


NORTH   DAKOTA    PAINT    TESTS  187 


Hail-stone  Abrasions  on  House  Repainting  Tests 


188 


PAINT  TECHNOLOGY  AND  TESTS 


— 7~ 


_  j 


Hail-stone  Effect,  West  Side  of  1907  Test  Fence 


NORTH  DAKOTA  PAINT  TESTS 


189 


eliminated  from  the  detailed  inspection,  only  general  observations 
of  these  tests  being  made.  These  general  observations,  however, 
showed  that  paints  Nos.  6  and  8  on  the  1906  fence,  and  paints 
Nos.  8,  10,  and  13  on  the  1907  fence,  proved  the  most  satisfactory 
on  the  western  exposure.1 


Peculiar  Crystallization  Effect   on  Section  41.    New  Special  Fence  Paint 
Applied  During  Cold  Weather 

"  Ochre  was  tried  out  as  a  priming  coat  on  several  formulas, 
but  it  was  found  to  be  most  unsatisfactory,  affecting  the  subse- 
quent coats  of  paint  and  causing  early  failure,  as  evidenced  by 
broad  checking,  discoloration,  and  general  bad  condition.  These 

1  These  formulas  were  the  same  as  those  respectively  numbered  on  the 
Atlantic  City  and  Pittsburg  fences. 


190  PAINT  TECHNOLOGY  AND   TESTS 

conditions  also  apply  to  those  panels  on  the  1908  fence  coated 
with  shellac  as  a  primer. 

"  The  colored  formulas  in  every  case  showed  a  great  superiority 
over  the  same  paints  in  white  untinted,  and  demonstrated  that 
a  percentage  of  color  has  a  wonderful  influence  on  the  preserva- 
tion of  the  paint  coating,  reducing  chalking,  checking,  and  general 
disintegration.  This  condition  is  probably  due  to  the  reinforcing 
value  of  the  color  pigments  used. 

"  It  is  safe  to  state  that  the  combination  formulas  tinted  yellow 
were  of  better  appearance  than  the  corroded  white  leads  tinted 
yellow,  the  latter  appearing  quite  dark  in  many  cases. 

"  The  wearing  of  the  paints  made  solely  from  white  lead  and 
zinc  oxide  seemed  to  indicate  that  a  percentage  of  a  third  pigment, 
of  an  inert  nature,  would  have  been  beneficial. 

"  The  high-type  mixtures  of  pigments  containing  lead  and 
zinc,  with  moderate  percentages  of  inert  pigments,  on  good  wood, 
were  in  most  excellent  general  condition;  in  fact,  much  superior 
to  the  single  pigment  paints.  Their  surface  exhibited  only  minor 
checking  and  moderate  chalking  with  good  maintenance  of  color, 
and  presenting  surfaces  well  adapted  to  repainting. 

"  The  sublimed  white  lead  was  in  fair  condition,  with  very 
little  checking,  and  offering  a  fair  repainting  surface.  The 
corroded  white  lead  was  somewhat  whiter  than  the  sublimed 
white  lead,  but  a  careful  observation  of  the  surface  of  the  corroded 
lead  revealed  deep  checking. 

"  It  was  clearly  demonstrated,  however,  that  in  climates  of 
the  North  Dakota  type,  white  lead  alone  is  not  entirely  satis- 
factory. The  addition  of  zinc  oxide  to  white  lead  forms  paint 
that  has  proved  much  superior  to  the  white  lead  alone. 

"  It  was  conclusively  demonstrated  that  mixtures  of  white 
lead  and  zinc  oxide,  properly  blended  with  moderate  percentages 
of  reinforcing  pigments,  such  as  asbestine,  barytes,  silica  and 
calcium  carbonate,  are  most  satisfactory  from  every  standpoint, 
and  are  superior  to  mixtures  of  prime  white  pigments  not  rein- 
forced with  inert  pigments. 

"  The  white  leads  painted  out  on  the  1908  fence  exhibited 
different  degrees  of  checking,  the  mild-process  lead  and  sublimed 
white  lead  which  presented  the  best  surfaces,  being  free  from 
checking,  while  the  old-process  leads  seemed  to  show  very  deep 
and  marked  checking,  even  after  one  year's  wear. 


NORTH  DAKOTA  PAINT  TESTS 


191 


Corroded  White  Lead  Sublimed  White  Lead 

Condition  of  Two  White  Leads  on  Two  Grades  of  Wood 


192 


PAINT  TECHNOLOGY  AND  TESTS 


Photomicrographic  Apparatus  and  Method  of  Use 


T  FENCE 

here,  on  side  of 


only 


881 

l!l 

§>! 
II! 

~Q.S 
§*§ 


FA 

the  paints.  F 


i 

" 


5  is 
22 


So 

^2 

0 


Ofa 


55     O 


:i; 


3-S.S     h 

;r  £ 


1   1   1  li  1 

O        O-"        O.        O 

=5     O5     O 


O     O 


II 


|  :    s    a     !    ss      s    i    s|s 

iiililrilri 


J9UQ  auiznag 


1    1    1    IS     -  III  S3 


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|si  I    I    I    I    I  I     2|  I  I  II  I    I 


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S3'  'si     I 


194 


PAINT  TECHNOLOGY  AND   TESTS 


CONDENSED   REPORT   OF   INSPE 
FARGO,  NORTH  DAKO 


FORMULAS 

Test 

No. 

PIGMENT 

VEHICLE 

«g 

1 

a 

14 

13 

1 

1 

T3:3 
003 

1 

55 

a 

•1 
Q 

TJ 

o 

C  £ 

£ 

t3 

•a 

£ 

6 

a 
2  | 

2 

3 

1 

V 

o 

1 

1 

11 

$ 

g 

g 

2 

JJ 

1 

1 

2 

3 

s 

•o 

1 

Ig 

^ 

Is 

s-  ^ 

"^  "^ 

o 

"o 

2  be 

i>> 

o 

"£ 

bfl 

'5 

0 

^ 

a 

-S 

a'  3 

aJ 

£3 

3 

J2   °3 

1 

55 

1 

5 

g 

a 

N 

a 

3 

EH 

II 

1 

H! 

1 

30 

— 

70 

— 

— 

— 

— 

— 

— 

— 

— 

93 

7 

— 

— 

— 

2 

50 

— 

50 

— 

— 

— 

— 

— 

— 

— 

— 

86 

— 

10 

4 

— 

3 

20 

20 

50 

10 







— 







90 







10 

4 

48.5 

— 

48.5 

3. 

— 

— 

— 

— 

— 

— 

— 

83 

— 

— 

— 

17 

5 

22 



50 

2 

26 



— 

— 

— 





90 









6 

-. 



64 



. 

36 

— 

— 







98 









7 

37 



63 



— 

— 

— 

— 

—    1    — 

85 

13 

— 

2 



8 

38 



48 





— 

14 

— 



1     

91 

9 



— 



9 

— 

73 

2 

— 

— 

25 

— 

— 

— 

— 

66 

— 

12 

22 

10 

44 



46 

5 







— 







86.0 

12.5 



1.5 



11 

50 

— 

50 



— 

— 

— 

— 

5 

— 

— 

78 

22 

— 

— 



12 

60 

— 

34 

— 

— 

— 

— 

6 

— 

— 

— 

91 

7 

— 

2 

— 

13 



60 

27 

3 







— 

10 





90 





— 



14 

25 

20 

25 

5 

— 

— 

— 

— 

— 

25 

— 

90 

— 

6 

— 

— 

15 

_ 

20 

40 

10 

_ 

_ 

_ 

_ 

_ 

_ 

30 

90 

_ 

8 

2 

_ 

16 

33 

i  nn 

33 

— 

34 

— 

— 

— 

— 

90 

— 

10 

— 

— 

17 

1  Q 

1UU 
i  nn 

/    *» 

)e  A) 

lo 
19 

1UU 

100 

( 

\  nn 

C) 

— 

— 

— 

— 

— 

— 

— 

— 

10 

gal.  oil 

reduc 

tio  n 

— 

20 

~ 

LUU 

nn 

21 
22 

1UU 

100 

23 
24 
25 
200 

100 
37.51 
38.95 
15.625 

"(Ty 
7.84 
4.81 

peC) 
25.87 
33.58 

20.36 
19.48 
1.875 

— 

— 

8.42 
3.18 

(Mic 
(Rail 

aigan 
way 
1.250 

Seal 
White 

White 
Lead) 
43.750 

Lead  ) 
32.250 

gal.  oil 
4.000 

reduc 

tio  n 
1.250 

for 

NORTH  DAKOTA   PAINT  TESTS 


195 


CTION   OF   "1907"   TEST   FENCE 
TA,  Nov.  19-23,  1909 


FORMU- 
LAS 

VEHICLE 

CHALKING 

REPORT  OF  CONDITION 

I 

10 
10 

1  1  1  B  1  M  1  1  !  1  1  II  III  MUol  ||  |  |  |  Volatile  Oil 

I 

4 
inir 

CHECKING 

HIDING 
POWER 

COLOR 

CONDITION  FOR 
REPAINTING 

Medium  .  .  . 
Medium  .  . 
Bad  

Considerable   with    1  a  t  e  r  a 
cracking 

Fair 

Fair 

Poor  surface;  too  hard 

Rather  poor 
Fair 

Medium 
Good 
Fair 
Poor 

Fair 

Medium 
Good 
Fair 

Not  very  good 
Good 

Medium;  some  washing 
shown 
Medium 
Medium 
Poor 
Poor 
Poor 
Fair 

Poor 
Fair 
Fair 
Good 
Excellent 
Fair 

Considerable   with    lateral 
cracking    
Medium  —  scaling  some    
Considerable    with   lateral 
cracking   .    .    . 

Good  .. 
Good  .  . 

Good  .  . 
Good  .. 
Medium 
Fair  .  .  . 
Good  .. 

Medium 
Good  .. 
Fair  .  .  . 

Fair 

Fair  .  . 
Good  .. 

Good  .  . 
Good  .. 
Medium 
Fair  .  .  . 
Good  .. 

Good  .. 
Good  .. 
Fair  .  .  . 

Fair 

Medium  .  .  . 
Slight 

Slight 

Medium  .  .  . 
Considerable 
Slight    i 
Not  evident  '. 

Medium  .  .  . 
Slight  
Considerable 

Medium  .  .  . 
Considerable 

Medium  .  .  . 
Medium  ... 
Bad 

Considerable    

Present;  long  cracks    
Surface  checking  
Considerable    with    lateral 
cracking  

Very  slight       ... 

Lateral  cracking  
Present    with    slight    cracking 
and  scaling 

Surface  checking  only    
Considerable    with   lateral 

Good  .. 
Medium 

Good  .. 
rair  .  .  . 
Good  .  . 
Fair  .  .  . 
Good  .. 
Good 

Good  .. 
Fair  .  .  . 

Good  .. 
Good  .. 
Fair  .  .  . 
Fair  .  .  . 
Fair  .  .  . 
Fair 

Medium 

Slight;  some  shelling  
\lligatoring;  deep  checking  .  . 
Alligatoring;  deep  checking  .  . 
Deep     
Slight 

Bad  
Bad  
Considerable 
Not  evident 

Medium  .  .  . 
Bad 

Considerable;  slight  cracking; 
scaling 

Fair 

Good  .. 
Good  .  . 
Good  .  . 
Good  .. 

Lateral  cracking;  split  
Medium  deep             

Good  .  . 
Good  .  . 
Fair 

Considerable: 
Considerable 
Medium  .  .  . 

Slight'  lateral  cracking              1 

Some;  lateral  cracking  
Bad  cracking     

Fair  .  .  . 
Good  .  . 

Good  .. 
Good  .. 

196         PAINT  TECHNOLOGY  AND  TESTS 

"As  before  stated,  the  committee  believes  that  a  serious  mis- 
take was  made  on  the  test  fence  in  painting  out  the  leads  and 
other  formulas  on  the  various  woods  without  any  special  attention 
to  reduction  to  suit  the  nature  of  the  wood,  thus  accounting 
largely  for  the  difference  of  the  wearing  of  the  paints  on  the 
different  woods. 

"  The  reduction  of  the  white  leads  especially  was  to  be  criti- 
cised in  these  tests,  in  many  cases  too  much  oil  and  not  sufficient 
turpentine  being  present  to  cause  penetration. 

"  The  application  of  paint  to  cedar  was  satisfactory  in  most 
all  cases,  and  this  wood  showed  much  better  results  than  the 
other  woods  upon  the  fences.  The  exudation  of  resinous  pitch 
on  the  hard  pine  was  extremely  serious,  in  some  cases  coming 
through  the  paint  in  large  streaks,  causing  bad  results. 

"It  is  to  be  regretted  that  the  house  repainting  tests  which 
were  conducted  are  of  no  special  value,  inasmuch  as  no  informa- 
tion is  on  file  as  to  the  composition  of  the  old  paints  originally 
on  the  houses  before  the  application  of  the  test  paints.  Imper- 
fections in  the  old  coating,  such  as  excessive  chalking,  deep  check- 
ing, scaling,  rosin  exudations,  etc.,  affected  the  subsequent  coats 
in  such  a  manner  as  to  prevent  any  knowledge  of  where  the  new 
and  old  paint  troubles  began.  The  committee,  therefore,  omitted 
a  detailed  inspection  of  such  tests. 

"  Examination  of  the  three  houses  which  were  painted  over 
new  wood  showed  results  which  correspond  with  the  results 
obtained  from  the  fence  tests.  That  is,  they  showed  the  ulti- 
mate value  of  high  type  mixtures  of  several  pigments  over  one 
pigment  alone.  These  tests  seem  to  indicate  that  very  good 
results  can  be  secured  from  most  of  the  paints  sold  in  North 
Dakota.  If  the  consumer  or  householder  would  exercise  more 
care  in  the  selection  of  wood  and  preparation  of  surfaces,  with 
due  regard  to  the  proper  reduction  for  various  coats,  more 
satisfactory  results  would  be  obtained. 

"  From  an  examination  of  certain  paints  on  the  1908  fence 
containing  petroleum  spirits,  it  would  appear  that  this  paint 
thinner  is  of  value,  and  in  the  face  of  conditions  such  as  are  pre- 
sented by  the  present  scarcity  of  turpentine,  the  use  of  petroleum 
spirits  in  moderate  quantity  would  be  justified." 


NORTH  DAKOTA  PAINT  TESTS 


197 


NORTH   DAKOTA   TESTS 


1.   Formula  No.  21,  Section 
31,  on  1907  Fence 


4.   Formula   No.   2,   Section 
3,  on  1907  Fence 


2.    Section  80,  on  1908  Fence 


5.   Formula  No.  1,  Section  1, 
on  1907  Fence 


3.   Formula  No.  6,  Section  9, 
on  1907  Fence 


6.   Formula  No.  14,  Section 
21,  on  1907  Fence 


198 


PAINT  TECHNOLOGY  AND   TESTS 
NORTH   DAKOTA   TESTS 


Formula    No.     13,    Panel 
19,  on  1907  Fence 


10.  Formula  No.  25,  Section 
37,  on  1907  Fence.  Good 
Condition.  Surface 
Checking  Only 


8.  Formula  No.  19,  Panel  28. 
Broad,  Deep  Checking  on 
Corroded  White  Lead  on 
1907  Fence 


11. 


Formula  No.  8,  Panel  12, 
on  1907  Fence 


9.  Formula  No.  24,  Panel  36, 
on  1907  Fence.  Good 
Condition.  Surface 
Checking  Only 


12.    Formula    No.    10,   Panel 
15,  on  1907  Fence 


NORTH   DAKOTA    PAINT   TESTS 
NORTH    DAKOTA   TESTS 


199 


13.  Panel  No.  34,  Formula 
23,  on  1907  Fence.  Deep 
Checking  on  Corroded 
White  Lead 


16.   Test   No.  2,    1906   Fence. 
Sublimed  White  Lead 


14.  Test  No.  13  on  1906 
Fence.  White  Spots 
Show  Paint  Left  on 
Wood.  Balance  of  Paint 
Split  and  Disintegrated 
from  Surface 


17.   Cracks  in  Test  No.  15  on 
1908  Fence 


15.  Test  No.  6  on  1906  Fence. 
Surface  Checking  Only 


18.  Effect  of  Cracking  on 
Hard  Pine,  Causing  Split- 
ting of  Painting  Coating 


200 


PAINT   TECHNOLOGY  AND   TESTS 
NORTH  DAKOTA  TESTS 


19.  Formula  No.  22,  Section 
23,  1907  Fence.  Cracks 
in  Paint  Coating,  Caused 
by  Cracks  in  Wood; 
Coating  Otherwise  i  n 
Good  Condition 


20.  Test  No.  8,  on  1906 
Fence.  Surface  Checking 
Only 


21.  Combination  Cracking 
and  Checking  on  Section 
69,  on  1908  Fence 


22.  Cracks  in  Paint  Coating, 
Caused  by  Cracking  of 
Hard  Pine  Wood 


23.  Section  65  on  1908  Fence. 
Showing  Early  Break- 
down  of  Corroded  White 
Lead 


CHAPTER  XIII 
TENNESSEE  PAINT  TESTS 

Location  and  Object  of  Tests.  On  September  15,  1910,  the 
erection  of  a  wooden  test  fence  was  completed  on  the  State  Fair 
Grounds  at  Nashville,  Tenn.  Upon  this  fence  were  exposed 
forty-two  samples  of  white  paint,  the  object  of  the  test  being 
to  determine  whether  the  combination  type  of  formula  is  superior 
to  the  single  pigment  type  in  the  southern  plateau,  of  which 
Nashville  is  the  centre. 

Construction  of  Tests.  The  construction  and  outline  of  these 
tests  differ  somewhat  from  those  conducted  at  Atlantic  City 
and  elsewhere  by  the  Scientific  Section.  The  fence  frame  is 
150  feet  long,  being  made  of  6-inch  bevelled  girders  supported 
three  feet  from  the  ground  by  4-inch  posts  set  six  feet  apart. 
Upon  this  girder  were  placed  a  series  of  forty-two  test  panels 
supported  at  top  and  bottom  with  weather  strips  and  braces. 
The  test  panels  used  were  40  inches  high,  30  inches  wide,  and 
one  inch  thick,  being  made  of  the  highest  grade  white  pine, 
tongued  and  grooved  together,  and  protected  on  the  edges  by 
weather  strips  projecting  from  the  surface  of  the  panels.  Each 
panel  was  painted  on  both  sides  with  the  same  paint,  thus  giving 
an  eastern  and  western  exposure,  the  fence  running  north  and 
south.  The  formulas  used  in  the  test  vary  in  their  percentage 
composition,  being  made  up  in  some  cases  of  single  pigments, 
and  again  with  combinations  of  the  opaque  white  pigments,  with 
and  without  certain  percentages  of  the  crystalline  or  inert  pig- 
ments. The  paints  were  applied  under  the  supervision  of  promi- 
nent master  painters  and  a  committee  representing  the  Scientific 
Section  and  other  technical  organizations. 

Other  field  tests  have  shown  that  the  sap  and  knots  in  hard- 
grained  woods,  such  as  yellow  pine,  cypress,  etc.,  have  been  the 
cause  of  the  failure  of  even  the  best  paints,  and  that  all  tests  should 
be  conducted  upon  soft  woods,  such  as  white  pine  and  poplar, 
if  definite  results  are  to  be  obtained.  Paints  tinted  with  ochre, 

201 


202 


PAINT  TECHNOLOGY  AND  TESTS 


chrome  yellow,  lampblack,  iron  oxide,  etc.,  have  shown  on  the 
other  field  tests  which  have  been  conducted  at  Atlantic  City, 
Pittsburg,  and  Fargo  the  value  of  these  pigments  in  giving  to 
the  paints  increased  wearing  properties.  On  the  Southern  Test 
Fence,  therefore,  all  the  formulas  were  ground  in  white  only  and 
placed  upon  white  pine  so  as  to  make  the  test  primarily  one  to  de- 
termine the  value  of  the  various  white  pigments  upon  good  wood. 
Oil  and  Thinner  Tests.  Upon  one  series  of  panels  on  the  fence 
was  placed  one  of  the  formulas  which  had  given  universal  satis- 
faction on  the  various  test  fences  in  the  past,  and  this  formula 
was  made  up  with  various  oils  other  than  linseed  oil,  in  order  to 


Tennessee  Test  Fences 

determine  the  value  of  these  oils  as  painting  materials.  For 
instance,  the  vehicle  part  of  the  one  formula  referred  to  is  made 
up  of  50%  linseed  oil  and  50%  soya  bean  oil,  and  again  50% 
linseed  oil  and  50%  rosin  oil,  etc.,  an  effort  being  made  to  test 
out  a  few  of  the  available  semi-drying  oils. 

The  same  formula  referred  to  was  ground  in  pure  linseed  oil 
and  subjected  to  a  series  of  tests  where  it  has  been  thinned  for 
application  as  priming  and  second  coats  with  a  series  of  wood 
turpentines  obtained  from  the  United  States  Forest  Products 
Laboratory  at  Madison,  Wis.  These  turpentines  were  made 
from  southern  pine  stumps  and  sawdust,  and  they  vary  greatly 
in  their  properties.  Some  were  objectionable  in  odor,  while 
others  were  of  excellent  quality,  having  an  odor  almost  equal 
to  that  of  pure  gum  spirits. 


TENNESSEE  PAINT  TESTS 


203 


Views  of  Fence 


204  PAINT  TECHNOLOGY  AND   TESTS 

One  product  under  test  on  the  Southern  Test  Fence  is  pine 
oil,  a  high  boiling  point  product  obtained  from  the  manufacture 
of  wood  turpentine  from  sawdust.  This  oil  has  a  boiling  point 
of  over  210  degrees  Centigrade  as  against  the  150  degrees  of 
ordinary  gum  spirits.  It  is  almost  water  white  and  has  the 
same  penetrating  qualities  as  the  pure  gum  spirits;  when  mixed 
with  50%  linseed  oil  forming  a  paint  oil  of  extremely  light  color, 
that  produces  a  semi-flat  paint  of  great  whiteness. 

Reductions  and  Application.  Formulas  No.  1  to  No.  37  were 
all  ground  in  pure  refined  linseed  oil.  They  were  made  in  the 
form  of  semi-paste  and  then  thinned  down  with  sufficient  refined 
linseed  oil  so  that  each  would  have  a  relative  viscosity.  To 
each  formula  was  then  added  a  sufficient  amount  of  pure  lead  and 
manganese  linoleate  drier  to  give  proper  drying  qualities.  On 
thinning  for  the  priming  coat,  one  pint  of  turpentine  was  added 
to  each  gallon  of  paint.  For  the  second  coat,  one-half  pint 
turpentine  and  one-half  pint  refined  linseed  oil  were  added  to 
each  gallon.  For  the  third  coat  work,  reduction  was  made  with 
one  pint  of  refined  linseed  oil. 

In  the  case  of  formulas  31  to  37,  reductions  were  the  same, 
except  that  a  series  of  specially  prepared  wood  turpentines  were 
used  in  place  of  the  pure  gum  spirits  used  in  formulas  1  to  31. 

Formulas  38  to  41,  as  will  be  shown,  were  ground  in  equal 
parts  of  the  oils  tested.  These  formulas,  however,  were  all 
thinned  for  application  with  pure  gum  spirits  of  turpentine, 
and  the  respective  vehicle  in  which  they  were  ground. 

No  inspection  of  the  Tennessee  Test  Fence  has  yet  been  made. 
The  formulas  tested  are  as  follows: 

FORMULAS   FOR  SOUTHERN  TEST  FENCE 

VEHICLE:   Bleached  Linseed  Oil  with  Lead  and  Manganese  Linoleate  Drier. 

Formula 
No. 

1  !  Corroded  white  lead   100% 

2  !  Sublimed  white  lead     100% 

3  Zinc  oxide  XX 100% 

4  Zinc  lead  white 100% 

5  Leaded  zinc  65%,  corroded  white  lead 35% 

6  i  Corroded  white  lead 100% 

7  *  Corroded  white  lead  100% 

1  Corroded  White  Lead  is  the  Basic  Carbonate  of  Lead.  Sublimed  White 
Lead  is  the  Basic  Sulphate  of  Lead. 


TENNESSEE  PAINT  TESTS 


205 


No.  8 

Corroded  white  lead 
Zinc  oxide   . 


85% 

15% 

100% 


No.  9 

Corroded  white  lead    65% 

Zinc  oxide   35% 

100% 

No.  10 
Corroded  white  lead    50% 


No.  18 

Corroded  white  lead    45% 

Zinc  oxide   40% 

Asbestine  . 15% 

100% 

No.  19 

Corroded  white  lead   45% 

Zinc  oxide   40% 

Barytes    15% 

100% 


Zinc  oxide   

.  .  .   50% 

No.  20 

100% 

Sublimed  white  lead   
Zinc  oxide   

....  45% 
40% 

No.  11 

Silica    

15% 

Corroded  white  lead    
Zinc  oxide   

...  40% 
.  ..  60% 

100% 

100% 

No.  21 
Sublimed  white  lead    . 

45% 

No.  12 

Zinc  oxide    

40% 

Corroded  white  lead  

.   30% 

Asbestine  

15% 

Zinc  oxide  

...  70% 

100% 

No.  13 

Corroded  white  lead    . 

Zinc  oxide   

Silica    . 


100% 


45% 

45% 

10% 

100% 


No.  14 
Corroded  white  lead    . 

Zinc  oxide    

Asbestine  . 


45% 

45% 

10% 

100% 


No.  15 

Corroded  white  lead   45% 

Zinc  oxide   45% 

China  clay 10% 

100% 

No.  16 

Corroded  white  lead    45% 

Zinc  oxide   45% 

Barytes    10% 

100% 

No.  17 
Corroded  white  lead  45% 

Zinc  oxide   40% 

Silica    15% 

100% 


No.  22 

Sublimed  white  lead    45% 

Zinc  oxide    40% 

Barytes    15% 

100% 

No.  23 

Zinc  oxide   90% 

Calcium  carbonate 10% 

100% 


No.  24 
Sublimed  white  lead    . 

Zinc  oxide    

Calcium  carbonate  .  . . 


40% 

45% 

15% 

100% 


.   35% 

.  50% 

.   15% 

100% 


No.  26 

Corroded  white  lead    20% 

Sublimed  white  lead    30% 

Zinc  oxide    40% 

Asbestine 10% 

100% 


No.  25 
Corroded  white  lead    . 

Zinc  oxide   

Silica    . 


206 


PAINT  TECHNOLOGY  AND   TESTS 


No.  27 

Corroded  wrhite  lead 

20% 

Sublimed  white  lead    .  . 

-  .   20% 

Zinc  oxide 

40% 

Barytes  '.    

....    10% 

Asbestine     

....    10% 

100% 

No.  28 

Corroded  white  lead    

....   20% 

Sublimed  white  lead    

....   20% 

Zinc  oxide   

....   40% 

Calcium  carbonate     

....    10% 

Silica    

10% 

100% 

No.  29 

Sublimed  white  lead    

.   20% 

Corroded  white  lead  

....   20% 

Zinc  oxide  

....   30% 

Barytes 

10% 

Asbestine  . 

10% 

Calcium  carbonate  

....          ±\J    /Q 

....   10% 

100% 

Formula 

No. 

No.  30 

Corroded  white  lead    . 

Zinc  oxide   

Barytes    


No.  31 

Corroded  white  lead    . 

Zinc  oxide   

Asbestine 

Calcium  carbonate  .  . 


33% 
33% 
33% 

99% 


45% 

45% 

5% 

5% 

100% 


32.  Same  as  No.  31  but  thinned  with  wood  turpentine  No.  1. 

33.  Same  as  No.  31  but  thinned  with  wood  turpentine  No.  2. 

34.  Same  as  No.  31  but  thinned  with  wood  turpentine  No.  3. 

35.  Same  as  No.  31  but  thinned  with  wood  turpentine  No.  4. 

36.  Same  as  No.  31  but  thinned  with  wood  turpentine  No.  5. 

37.  Same  as  No.  31  but  thinned  with  high-boiling-point  petroleum  spirits 

(turpentine  substitute). 

38.  Same  as  No.  31  but  ground  in  50%  raw  linseed  oil,  50%  soya  bean  oil. 

39.  Same  as  No.  31  but  ground  in  50%  raw  linseed  oil,  50%  corn  oil. 

40.  Same  as  No.  31  but  ground  in  50%  raw  linseed  oil,  50%  cotton  seed  oil. 

41.  Same  as  No.  31  but  ground  in  50%  raw  linseed  oil,  50%  rosin  oil. 

42.  Same  as  No.  31  but  ground  in  50%  raw  linseed  oil,  50%  pine  oil. 


CHAPTER  XIV 
WASHINGTON   PAINT  TESTS 

THE  new  vehicle  test  fence  at  Washington  is  fully  described 
in  the  writer's  paper  l  as  presented  before  the  American  Society 
for  Testing  Materials,  as  follows: 

"  The  high  price  attained  by  linseed  oil  during  the  past  two 
years  of  over  a  dollar  a  gallon,  together  with  the  unusual  scarcity 
of  this  valuable  oil,  has  led  many  investigators  into  the  field  of 
research,  with  a  view  of  discovering  some  mixture  of  other  oils  to 
partly  replace  linseed  oil.  Many  valuable  contributions  to  oil 
technology  have  resulted,  but  the  makers  and  users  of  paints  have 
wisely  demanded  specific  and  authoritative  information  as  to  the 
practical  value  of  proposed  mixtures  before  adopting  them.  The 
Institute  of  Industrial  Research,  at  the  request  of  the  Paint 
Manufacturers'  Association  of  the  United  States,  has  recently 
started  a  series  of  practical  paint  vehicle  tests  designed  to  decide 
the  question  at  issue. 

"  Forty-eight  white-pine  panels  have  been  placed  upon  a  test 
frame  on  the  grounds  of  the  new  laboratory  building  of  the  Insti- 
tute, at  Washington,  D.  C.  They  are  painted  with  a  standard 
white  pigment  formula  reduced  with  a  different  oil  formula  for 
every  panel.  White-pine  panels  were  selected  for  the  test  on 
account  of  the  good  painting  surface  which  this  type  of  lumber 
presents;  the  grade  selected  was  free  from  knots  or  pitch  pockets 
—  defects  which  often  ruin  a  paint  test.  Each  panel  was  con- 
structed of  four  tongued-and-grooved  planed  boards,  22  inches 
long,  1  inch  thick,  and  9  inches  wide.  The  boards  were  leaded 
together  and  capped  at  the  sides  with  weather  strips,  making  the 
finished  panels  about  2  feet  wide  and  3  feet  high.  The  fence 
upon  which  the  panels  were  placed  was  constructed  of  4-inch 
squared  yellow  pine  with  open  framework,  allowing  the  panels 

1  The  Practical  Testing  of  Drying  and  Semi-Drying  Paint  Oils,  by  Henry 
A.  Gardner.  Paper  presented  at  Fourteenth  Annual  Meeting,  Amer.  Soc. 
for  Test.  Mater.,  Atlantic  City,  N.J.,  June,  1911. 

207 


208 


PAINT  TECHNOLOGY  AND  TESTS 


a  resting  place  upon  which  they  were  finally  secured  with  sher- 
ardized  screws. 

"  Before  erecting  the  panels,  they  were  carefully  painted  in  a 
paint  laboratory  especially  fitted  out  for  the  tests.  The  work 
was  done  during  the  months  of  April  and  May,  the  temperature 
averaging  from  60  degrees  to  90  degrees  Fahrenheit.  This 
precaution  was  taken  in  order  that  the  paint  in  each  case  might 
become  thoroughly  dry  and  hard  before  exposure,  so  that  there 
would  be  no  accumulation  of  dust  or  effect  from  exposure  during 
the  drying  period.  The  actual  painting  of  each  panel  was  done 
personally  by  Mr.  Charles  Macnichol,  master  painter,  of  Wash- 
ington, D.  C.,  who  has  had  a  wide  experience  in  the  practical 
application  and  testing  of  paints. 


View  of  Panels  on  Washington  Test  Fence 

"  The  viscous  nature  of  several  of  the  oils  tested  precluded 
the  possibility  of  grinding  each  oil  formula  with  the  white  pigment 
base  selected;  great  heating  of  the  paint  mills  and  a  paste  of 
insufficient  fineness  was  the  result  of  an  early  attempt  at  this 
method.  It  was  decided,  therefore,  to  grind  the  standard  pig- 
ment formula  to  a  thick  paste  in  the  minimum  amount  of  raw 
linseed  oil.  Subsequently  a  weighed  amount  of  the  white  pig- 
ment base  was  thinned  with  the  oil  formula  to  be  tested,  to  a 
standard  viscosity,  judged  by  the  experienced  master  painter 
in  charge  of  the  practical  application  of  the  formulas  as  sufficiently 
heavy  for  third-coat  work.  When  making  the  reductions  with 
oil  mixtures,  an  allowance  was  made  for  the  amount  of  linseed 
oil  already  contained  in  the  ground  white  pigment  base. 

"  During  the  application  of  the  first  coat  an  equal  amount  of 
turpentine  was  added  to  each  formula,  in  the  proportion  of  one- 


WASHINGTON  PAINT  TESTS  209 

half  pint  to  a  gallon  of  paint;  in  the  application  of  the  second 
coat  there  was  added  to  each  formula  a  like  amount  of  an  equal 
mixture  of  turpentine  and  the  oil  formula  under  test.  The 
third  coat  was  applied  without  the  addition  of  thinners  of  any 
kind. 

"It  is  well  known  that  the  time  of  drying  and  the  condition  of 
the  dried  film  of  any  oil  or  mixture  of  drying  or  semi-drying  oils 
will  vary  widely.  It  is  for  the  purpose  of  causing  oils  to  set  up 
to  a  hard  film  in  a  short  time  that  metallic  driers  in  the  form  of 
salts  of  manganese  and  lead,  soluble  in  oil,  are  added  to  a  paint. 
Some  oils  require  a  large  amount  of  drier,  while  others  require 
only  a  very  small  amount.  Those  which  require  a  large  amount 
are  apt,  upon  exposure,  to  be  burned  up  by  the  drier,  resulting 
in  the  formation  of  a  powdered  and  disintegrated  film.  To  add 
various  types  of  drier  or  even  differing  amounts  of  a  drier  to  the 
oils  under  test,  seemed  very  unfair  from  every  standpoint,  and 
it  was  therefore  decided  to  eliminate  the  drier  question  entirely, 
so  as  not  to  vitiate  the  results  by  bringing  in  a  factor  of  this 
nature.  The  plan  of  omitting  driers  proved  successful  in  the 
Atlantic  City  steel-panel  paint  tests,  erected  three  years  ago  by 
the  writer  under  the  supervision  of  Committee  A-5  of  this 
Society. 

"  The  systematic  methods  which  are  necessary  when  making 
paint  tests  were  carefully  followed.  A  standard  weighed  amount 
of  white  pigment  paste  was  placed  in  a  clean  paint  cup  and 
thinned  to  the  proper  consistency  with  a  weighed  amount  of  the 
oil  under  test.  Proper  reductions  were  made,  as  before  stated. 
Weighings  of  the  paint,  cup,  and  brush  were  made  before  and 
after  application  to  the  panel,  in  order  to  determine  the  quantity 
of  paint  used  and  the  spreading  power.  A  period  of  fifteen  days 
was  allowed  between  the  application  of  successive  coats,  in  order 
to  give  each  formula  sufficient  time  to  dry  thoroughly.  Although 
several  of  the  formulas  remained  tacky  for  over  a  week,  all  dried 
thoroughly  in  the  time  allotted.  (Oils  which  when  used  alone 
have  slow  drying  properties,  have  been  found  to  yield  good  firm 
films  when  used  with  drying  pigments  such  as  lead  and  zinc.) 
The  backs  and  edges  of  each  panel  were  painted  with  two  coats 
of  the  paint  used  on  the  face  of  the  panel,  so  as  to  prevent  the 
admission  of  moisture.  After  erection,  the  panels  were  numbered 
with  aluminum  figures  pressed  into  the  surface.  Frequent 


210  PAINT   TECHNOLOGY  AND   TESTS 

inspections  will  be  made,  and  at  the  proper  time  reports  will 
be  issued  giving  the  results  of  the  tests. 

"  During  the  painting  of  the  panels  considerable  interesting 
data  were  collected,  of  which  the  following  is  a  brief  resume: 

"  The  hiding  power  of  a  paint  is  one  of  its  most  important 
requisites.  It  was  found  in  the  tests  that  some  oils  had  the  effect 
of  lessening,  while  others  had  the  effect  of  increasing  the  hiding 
power  of  the  standard  pigment  formula.  This  may  be  due  in 
part  to  the  varying  refractive  indices  of  the  oils  used,  as  well  as 
to  the  difference  in  the  quantity  of  oil  required  in  each  test. 
Some  oils  were  very  viscous,  while  others  were  very  light. 

"  The  stiff  working  of  heavy-bodied,  blown,  or  heat-oxidized 
oils,  produced  films  which  in  some  cases  gave  a  very  glossy  sur- 
face, even  on  the  priming  coat.  Some  of  these  resembled  var- 
nished work  when  finished.  It  will  be  of  importance  to  watch 
these  tests  carefully  for  any  signs  of  early  breakdown,  which 
might  come  from  too  thick  a  film.  The  treated  Chinese  wood 
oil  paints  worked  rather  stiff  but  produced  very  smooth  films. 
The  rosin  oil  paints  became  slightly  lumpy  on  standing,  but 
worked  out  to  a  smooth  finish  somewhat  yellowish  in  color. 
The  marine  animal  oils,  especially  the  menhaden  oil  mixtures, 
dried  to  a  film  slightly  flatter  than  straight  linseed  oil.  Any 
odor  which  was  present  in  the  paints  made  from  the  animal  oils 
seemed  to  disappear  a  few  hours  after  application.  The  cotton 
seed  and  corn  oil  mixtures  made  the  slowest  drying  paints,  but 
at  the  end  of  the  second  week  of  the  drying  period  they  set  up 
rapidly  to  firm  films.  Soya  bean  and  perilla  oils  behaved  like 
straight  linseed  oil,  the  former  being  a  little  slower  and  the  latter 
slightly  more  rapid  in  drying  properties.  The  perilla  oil  was 
made  from  one  of  the  first  importations  into  this  country,  and 
was  dark  in  appearance.  It  made,  however,  a  very  easy-working 
and  hard-drying  paint. 

"  The  oils  used  in  the  tests  were  obtained  from  reliable  sources. 
After  they  were  received,  they  were  carefully  analyzed.  The 
results  of  the  analyses  appear  in  Table  I. 


WASHINGTON  PAINT  TESTS  211 

TABLE  1.     ANALYSES  OF  OILS  USED  IN  THE  VEHICLE  TESTS 


Specific 
Gravity 

Saponi- 
ficp.tion 
Number 

Iodine 
Number 

Acid 
Number 

Raw  linseed  oil                         

0.931 

188 

186 

20 

Boiled  linseed  oil  (linoleate  type)    .  . 
Boiled  linseed  oil  (resinate  type)  .  .  . 
Blown  linseed  oil    

0.941 
0.930 
0.968 

187 

186 
189 

172 
176 
133 

2.7 
2.2 

28 

Lithographic  linseed  oil  

0.970 

199 

102 

27 

Soya  bean  oil 

0.924 

189 

129 

2  3 

Menhaden  oil 

0.932 

187 

158 

3  9 

Perilla  oil                 .                

0.94 

188 

180 

20 

Chinese  wood  oil  (raw)   
Chinese  wood  oil  (treated)  *     

0.944 

0.898  1 

183 

128  ! 

166 
104* 

3.8 
681 

Corn  oil 

0.925 

191 

118 

95 

Cottonseed  oil 

0.921 

193 

105 

3  6 

Rosin  oil 

0.966 

27 

41 

167 

Whale  oil                                .    . 

0.924 

191 

148 

Neutral  petroleum  oil2    

0.916 

6 

12 

— 

1  Low  constants  due  to  presence  of  over  40%  of  volatile  matter,  largely 
petroleum  spirits. 

2  This  oil  contained  over  20%  of  petroleum  spirits. 

"  The  pigment  formula  selected  for  the  tests  had  the  following 
composition: 

Basic  carbonate-white  lead    20% 

Sublimed  white  lead    30% 

Zinc  oxide  .  . 35% 

Magnesium  silicate    10% 

Barytes    5% 

100  Ibs.  of  pigment  base  ground  to  a  stiff  paste  in  16  Ibs.  of  linseed  oil. 

"While  this  pigment  formula  was  not  selected  as  being  superior 
to  certain  other  formulas,  it  is  of  a  type  that  has  given  very  fair 
service  in  paint  tests  throughout  the  country,  and  will  no  doubt 
serve  admirably  for  the  purpose  designed  in  these  tests. 

"  The  vehicle  formulas  in  the  finished  paints  are  as  follows: 


No.  1 
Raw  linseed  oil 100% 


Soya  bean  oil 


Menhaden  oil 


No.  21 


No.  32 


No.  5 

Raw  linseed  oil 25% 

Boiled  linseed  oil  (linoleate)  . .     75% 


100% 
100% 


No.  6 

Raw  linseed  oil 

Boiled  linseed  oil  (resinate) 


No.  7 

Raw  linseed  oil 

Boiled  linseed  oil  (linoleate) 


No.  4 

Raw  linseed  oil 25% 

Boiled  linseed  oil  (resinate)    .  .     75% 

1  Dry  pigment  formula  in  soya  bean  oil. 

2  Dry  pigment  formula  in  menhaden  oil. 


50% 
50% 


50% 
50% 


212 


PAINT  TECHNOLOGY  AND   TESTS 


No.  8 


No.  23 


Raw  linseed  oil  ... 
Blown  linseed  oil 

50% 
50% 

Raw  linseed  oil  .  .  . 
Cottonseed  oil 

.     75% 
•     25% 

No 
Raw  linseed  oil 

.9 

50% 

No. 
Raw  linseed  oil 

24 

75% 

Litho  linseed  oil 

50% 

Rosin  oil 

25% 

No. 
Raw  linseed  oil 

10 

50% 

No. 
Raw  linseed  oil  . 

25 

50% 

Soya  bean  oil 

50% 

Soya  bean  oil  

25% 

No. 
Raw  linseed  oil 
Menhaden  oil  

11 

50% 

50% 

Menhaden  oil 

No. 
Raw  linseed  oil 

26 

-     25% 
.   50% 

Soya  bean  oil    .  .  .  , 

25% 

No. 

12 

Treated  wood  oil 

25% 

Raw  linseed  oil 
Perilla  oil  

No. 

13 

50% 
50% 

No. 
Blown  linseed  oil    . 
Soya  bean  oil    .  .  . 

27 

-  .  50% 

50% 

Raw  linseed  oil 
Treated  wood  oil    . 

50% 
50% 

No. 
Raw  linseed  oil 

28 

.  25% 

No. 

14 

Soya  bean  oil  .  . 

25% 

Raw  linseed  oil  .  .  . 

50% 

OKcr 

Corn  oil   

50% 

Treated  wood  oil 

.  .   Zo  /o 
.  .   25% 

No. 
Raw  linseed  oil  .  .  . 

15 

50% 

No, 
Raw  linseed  oil  . 

.29 

25% 

Cottonseed  oil 
No. 

16 

50% 

Soya  bean  oil 
Menhaden  oil  .  .  . 
Corn  oil   

-  .   25% 
-.   25% 
•  25% 

Raw  linseed  oil  .  .  . 
Rosin  oil 

50% 

50% 

"Mr* 

1  7 

No. 
Raw  linseed  oil 

30 

•  25% 

Kf\C/ 

Soya  bean  oil    . 

25% 

Raw  linseed  oil  .  .  . 

oU  7o 

K()C/ 

Menhaden  oil  .... 

•  •  25% 

Wnaie  on  

ou  /Q 

Cottonseed  oil    .  . 

25% 

No. 
Raw  linseed  oil 

18 

.   75% 

No. 

31 

25% 

Raw  linseed  oil  .  . 

.   25% 

No. 

19 

7KC/ 

Soya  bean  oil    ... 
Menhaden  oil  ... 
Rosin  oil 

.  .  25% 
-  .   25% 
25% 

Menhaden  oil 

to  /o 

.:...     25% 

No. 
Raw  linseed  oil  . 

20 

.   75% 

No. 
Raw  linseed  oil  .  . 
Soya  bean  oil    .  .  . 

32 

..   25% 
•  •   25% 

Perilla  oil 

25% 

Treated  wood  oil 

25% 

Rosin  oil    

25% 

No. 
Raw  linseed  oil    .  . 
Treated  wood  oil    . 

21 

75% 
25% 

No. 
Raw  linseed  oil 

33 

20% 

Soya  bean  oil    . 

20% 

No. 

22 

Treated  wood  oil 

20% 

Raw  linseed  oil  . 

.   75% 

Menhaden  oil   ... 

-   20% 

Corn  oil  .  . 

.   25% 

Cottonseed  oil    . 

.   20% 

WASHINGTON  PAINT  TESTS  213 

No.  34  No.  39 

Raw  linseed  oil  .............  20%  Raw  linseed  oil  ...........  ...  75% 

Soya  bean  oil    ..............  20%  Reducing  oil  2  .............       25% 

Treated  wood  oil   ...........  20%  M      ,n 

::::::::::::::  S  " 


No.  35  Neutral  petroleum  oil  ........   15% 

Raw  linseed  oil  .............  40%  NO  4^ 

Soya  bean  oil    ..............  20%  RaW  linseed  oil  .  50% 

Corn  oil  ...................  20%  Soya  bean  oil   ...  25% 

Cottonseed  oil  .    .  .....  ...  .  .  .  20%  Neutral  petroleum  oil   ........   15% 

No  36  Tungate  drier  ...  .10% 

Whale  oil  .......  '  ...........     33%  No.  42 

Treated  wood  oil   ...........     33%    Linseed  oil  ..................  25% 

Raw  linseed  oil  .............     33%    Soya  bean  oil   ...............  37% 

Neutral  petroleum  oil  ........  23% 

„       ..  ..No-  37  __„     Tungate  drier  ...............  15% 

Raw  linseed  oil  .............     25% 

L.  O.1  .  75%  No-  43 

Raw  linseed  oil  ..............  25% 

No.  38  Soya  bean  oil   ...............  37% 

Raw  linseed  oil  .............     50%    Whale  oil  ,  ..................  19% 

Raw  Chinese  wood  oil  .......     50%    Tungate  drier  ...............  19% 

No.  44 

Special  test  on  white  base  of  the  following  composition,  in  pure  linseed  oil  : 
Asbestine  ......................................   10% 

Corroded  white  lead    ............................  20% 

Sublimed  white  lead    ............................   30% 

Zinc  oxide  .....................................  40% 

Upper  board  of  panel  reduced  with  straight  turpentine  on  priming  coat. 

Second.board  of  panel  reduced  with  wood  turpentine  on  priming  coat. 

Third  board  of  panel  reduced  with  pine  oil  on  priming  coat. 

Bottom  board  of  panel  reduced  with  petroleum  spirits  on  priming  coat. 

No.  45 
Same  pigment  formula  as  No.  44,  reduced  with: 

Pine  oil    ...............................  ........   50% 

Linseed  oil  .....................................  50% 

No.  46 

Special  test  of  white  base  of  the  following  composition,  in  pure  linseed  oil: 
Corroded  white  lead  .............................  20% 

Sublimed  white  lead    ............................  30% 

Zinc  oxide  .....................................   35% 

Asbestine  ......................................   15% 

No.  47 
Cypress  panel  unpainted. 

No.  48 

Cypress  panel  painted  with  formula  No.  1,  thinned  with  benzol  on  the 
priming  coat. 

1  Mixture  of  boiled  tung  and  soya  bean  oil,  thinned  with  petroleum  and 
turpentine. 

2  25%  raw  linseed  oil. 
73%  petroleum  oil. 

2%  drier  —  lead  and  manganese  linoleate.'' 


CHAPTER  XV 
CEMENT  AND  CONCRETE  PAINT  TESTS 

Damp-proofing  and  Waterproofing.  The  decoration  and 
preservation  of  cement  and  concrete  is  a  subject  which  is  being 
given  the  careful  consideration  of  many  technologists  on  account 
of  the  wide  usage  of  cement  for  structural  purposes,  and  the 
necessity  of  properly  guarding  it  against  the  destructive  effects 
of  moisture. 

To  obtain  with  various  paints  decorative  effects,  and,  at  the 
same  time,  provide  a  high  degree  of  damp-proofing,  is  a  process 
quite  distinct  from  that  of  water-proofing  cement  and  concrete 
superstructures.  The  use,  in  small  percentage,  of  stearic  acid 
solutions,  aluminum  stearate,  marine  animal  soaps,  and  other 
lime-reacting  materials,  as  a  component  of  concrete  while  it  is 
being  mixed,  has  been  in  practice  for  some  time,  the  resulting 
mixture  being  used  largely  upon  base-work  subjected  to  water 
under  high  pressure.  Although  some  of  the  materials  used  for 
such  purposes  actually  do  give  to  the  concrete  a  high  power  of 
water  resistance,  the  degree  of  waterproofing  to  be  obtained 
through  the  use  of  many  such  compounds  varies  to  a  wide 
extent,  often  interfering  with  the  lime-silica  reactions,  and  ulti- 
mately affecting  the  strength  of  the  finished  concrete. 

Decorative  and  Preservative  Coatings.  The  necessity  of 
obtaining  suitable  paint  coatings  for  cement  and  concrete  sur- 
faces suggested  to  the  writer  a  series  of  tests  on  paints  designed 
to  prevent  the  destructive  action  of  the  lime  which,  by  seepage 
and  other  physical  action,  is  brought  to  the  surface,  causing 
saponification  of  some  oil  coatings,  as  well  as  destruction  of  color. 
The  tests  referred  to  were  carried  out  during  1908,  and  although 
great  advances  have  been  made  since  that  time  in  the  preparation 
of  concrete  paints,  the  tests  have,  nevertheless,  afforded  informa- 
tion of  a  valuable  nature  as  indicating  the  proper  methods  to 
follow  in  the  painting  of  cement,  as  well  as  suitable  materials  to 
use  in  the  manufacture  of  cement  paints.  The  tests,  moreover, 
show  the  comparative  durability  of  a  number  of  paints  typical  of 
those  prominent  in  the  market  at  the  time  the  tests  were  started. 

214 


CEMENT  AND  CONCRETE  PAINT  TESTS  215 

Acid  Reacting  Compounds.  A  series  of  acid  reacting  washes 
were  included  in  the  tests,  having  been  designed  as  prime  coaters 
for  use  previous  to  the  application  of  oil  paints.  The  application 
of  many  of  these  washes  has  the  effect  of  neutralizing  the  lime 
within  cement  and  concrete  surfaces,  and  often  precipitate  in- 
soluble lime  compounds  which  aid  in  filling  up  the  outer  voids, 
thus  presenting  a  surface  more  suitable  to  receive  oil  coatings. 
To  the  writer  who  has  since  made  a  careful  study  of  the  painting 
of  concrete,  it  would  seem  advisable  for  painters  to  avoid,  when 
possible,  the  use  of  these  lime  neutralizing  washes,  as  some  of 
them  have  more  or  less  disintegrating  and  weakening  influences 


View  of  Concrete  Paint  Test  Panels 

upon  concrete.  Recent  laboratory  experiments,  however,  have 
indicated  that  zinc  sulphate,  an  acid  reacting  material  used  for 
many  years  as  a  wash  for  concrete  surfaces  by  Macnichol,  actually 
has  a  strengthening  effect  upon  cement  and  concrete  surfaces. 
The  more  successful  coatings  of  to-day,  however,  are  those  which 
may  be  placed  directly  upon  the  cement  and  concrete  surfaces 
without  the  aid  of  such  washes.  Several  fairly  successful  paints 
of  this  type  have  recently  appeared  in  the  market;  some  of  them 
being  made  of  acid  rosins  compounded  with  vegetable  oils. 
Probably  one  of  the  first  mixtures  of  this  sort  was  the  so-called 
suction  varnish  which  the  master  painter  has  for  years  used  as 
a  prime  coating  on  plastered  walls  previous  to  painting.  These 
suction  varnishes  generally  contain  a  high  percentage  of  rosin, 


216         PAINT  TECHNOLOGY  AND  TESTS 

a  material  having  an  exceptionally  high  acid  value  and  thus 
lending  itself  successfully  to  the  neutralization  of  free  lime. 
It  has  been  claimed,  however,  by  certain  practical  painters  that 
the  lime-rosin  compounds  formed  when  such  paints  are  applied 
to  the  exterior  of  buildings,  are  of  a  brittle  nature  and  subject 
to  early  failure.  If  this  is  true,  it  would  seem  advisable  to  use 
in  a  concrete  paint  an  oil  of  a  relatively  unsaponifiable  nature, 
which  would  withstand  successfully  the  action  of  the  lime,  and, 
at  the  same  time,  prevent  disruption  of  the  coating  and  failure 
of  the  color  used  in  the  paint. 

Outline  of  Tests.  The  tests  referred  to  as  carried  out  by  the 
writer  were  made  on  a  brick  wall  forty  feet  long,  surface-coated 
with  a  four-inch  coating  of  Portland  cement  mortar  made  of  one 
part  of  Portland  cement  and  three  parts  of  sharp,  clean  sand. 
After  the  cement  had  hardened  for  three  days,  the  solutions  under 
test  were  applied. 

In  many  of  the  tests  outlined  above,  one-coat,  as  well  as  two- 
coat  work,  was  used  on  different  sections  of  the  test  surfaces. 
It  was  shown  that  the  two-coat  work  gave  far  better  results  than 
with  the  one-coat  work,  and  the  writer  would  recommend  for 
the  painting  of  concrete  at  least  two-coat  work.  Whenever 
paints  containing  Prussian  blue  or  chrome  green  are  applied  to 
concrete  surfaces,  immediate  whitening  in  the  case  of  the  blue, 
and  yellowing  in  the  case  of  the  green,  will  take  place,  if  any 
degree  of  action  has  been  exerted  by  the  lime  within  the  con- 
crete. For  this  reason,  green  is  an  especially  delicate  color  to 
test  and  should  be  utilized  for  this  purpose. 

The  materials  used,  and  the  results  shown  at  an  inspect' on 
made  after  two  years'  exposure,  are  given  herewith. 

Test  No.  i.  Concrete  primed  with  a  25%  solution  of  zinc 
sulphate  ^.crystals  dissolved  in  water.  A  wide  brush  was  used 
for  the  application,  and  the  spreading  rate  was  approximately 
200  square  feet  per  gallon.  Second  and  third  coated  on  the 
second  day  with  No.  119  blue  paint  of  the  following  composition: 

No.  119  BLUE  PAINT 

Sublimed  white  lead    50% 

Zinc  oxide   35% 

Silica  and  barytes    12% 

Prussian  blue    3% 

Ground  in  linseed  oil,  turpentine  and  drier. 


CEMENT  AND  CONCRETE  PAINT  TESTS  217 

This  panel,  after  three  years'  exposure,  is  in  good  condition. 
Slight  checking  observed. 

Test  No.  2.  Concrete  primed  with  a  20%  solution  of  (alum) 
(aluminum  sulphate).  Second  and  third  coated  with  No.  119 
blue. 

In  similar  condition  to  Test  No.  1. 

Test  No.  3.  Concrete  primed  with  zinc  sulphate  followed  by 
two  coats  of  para  red. 

PARA  RED  FORMULA 

Blanc  fixe    60% 

Whiting 25% 

Zinc  oxide   3% 

Paranitraniline  lake 12% 

Ground  in  linseed  oil,  turpentine  and  drier. 

Panel  in  fair  condition  with  exception  of  slight  crazing.  Char- 
acteristic dullness  of  color  after  exposure  shown.  Bright  red 
color  restored  upon  washing. 

Test  No.  4.  Concrete  primed  with  an  8%  solution  of  stearic 
acid  and  rosin  dissolved  in  benzine.  Second  and  third  coated 
with  No.  119  blue. 

This  panel  is  not  in  as  good  condition  as  Tests  Nos.  1  and  2, 
and  would  indicate  the  inferiority  of  the  priming  liquid  used. 
Color  failing  in  spots  and  checking  observed. 

Test  No.  5.  Concrete  primed  with  mixture  used  in  Test  No. 
4,  and  then  given  two  coats  of  para  red. 

Test  is  in  about  the  same  condition  as  No.  4. 

Test  No.  6.  Concrete  primed  with  a- 10%  mixture  of  acid 
calcium  phosphate,  followed  with  two  coats  of  No.  119  blue. 

The  acid  phosphate  solution  evidently  had  a  neutralizing 
effect  upon  the  lime  in  the  concrete,  as  the  paint  is  in  fair  condi- 
tion. 

Test  No.  7.  Concrete  primed  with  one  coat  of  a  soap  emulsion 
of  the  following  composition,  then  painted  with  two  coats  of  No. 
119  blue. 

Water 85% 

Linseed  oil 12% 

Alkali 3% 

Very  poor  results  obtained.  Destruction  of  color  and  peeling 
resulted. 


218         PAINT  TECHNOLOGY  AND  TESTS 

Test  No.  8.  Concrete  primed  with  one  coat  of  white  paint 
of  the  following  composition: 

PRIMER 

Zinc  oxide   .                  25% 

Silica    35% 

Corroded  white  lead    20% 

Gypsum 15% 

Whiting,  etc 5% 

Ground  in  a  vehicle  of  linseed  oil  and  containing  35%  of  volatile  hydro- 
carbon spirits  and  drier. 

This  coat  was  followed  by  one  of  the  following  composition, 
tinted  blue: 

Zinc  oxide   60% 

Gypsum 20% 

Silica    20% 

Ground  in  linseed  oil  with  12%  of  turpentine  and  drier. 

Fair  results  shown  during  first  year,  but  a  breakdown  occurred 
during  the  second  year,  and  cracking  and  scaling  resulted. 

Test.  No.  9.  This  test  was  a  duplicate  of  No.  8  with  the 
addition  of  5%  of  zinc  sulphate  solution  emulsified  into  the 
primer. 

Slightly  superior  to  Test  No.  8. 

Test  No.  10.  Primed  with  a  white  paste  paint  thinned  with 
turpentine.  Second  coated  with  same  paint  tinted  blue. 

FORMULA  OF  PASTE 


Whiting  30% 

Silica    20% 

Alumina  and  gypsum    10% 

of  linseed  oil  vehicle. 

Scaling  and  peeling  due  to  lack  of  binder  and  use  of  sapon- 
ifiable  oil  resulted  during  the  first  six  months'  exposure.  Entire 
destruction  of  coating  at  end  of  two  years. 

Test  No.  ii.  Primed  with  a  white  mixture,  and  second  coated 
with  the  same  mixture  tinted  blue. 

FORMULA  OF  MIXTURE 

Whiting 30% 

Silica    30% 

Zinc  oxide   40% 

Stirred  into  a  5%  solution  of  glue  in  water,  until  a  fairly  thick  paste  was 
obtained. 


CEMENT  AND  CONCRETE  PAINT  TESTS  219 

Much  chalking  was  shown,  and  a  bleaching  of  color.  It  is 
evident  that  this  mixture  would  not  serve  to  keep  moisture  out. 

Test  No.  12  A.  Primed  with  a  5%  solution  of  soluble  nitrated 
cotton  and  paraffin  dissolved  in  equal  parts  of  amyl  acetate 
and  benzine.  Second  coated  with  No.  119  blue. 

Not  very  good  results  were  obtained,  chalking  and  slight 
scaling  resulting. 

Test  No.  12  B.  Primed  with  a  heavy  varnish  containing 
Chinese  wood  oil  and  kauri  gum.  Second  coated  with  No.  119 
blue. 

Fair  results  obtained. 

Tests  Nos.  13,  14,  15,  and  16.  Primed  with  a  solution  made 
by  dissolving  10  parts  of  sodium  oxalate  in  100  parts  of  water. 
Second  and  third  coated  with  linseed  oil  paints  in  red,  brown, 
blue,  and  green. 

Very  good  results  shown  at  end  of  test. 

Test  No.  20,  Special.  Primed  and  second  coated  with  a  green 
paint  containing  zinc  oxide  and  barytes,  ground  in  an  oil  having 
a  low  saponification  value.  Very  slow  drying  was  shown. 
Excellent  results.  No  failure  of  color.  Extremely  glossy, 
waterproof  surface  presented. 


CHAPTER   XVI 
STRUCTURAL  STEEL  PAINT  TESTS 

The  Necessity  of  Protective  Coatings.  Most  painters  have 
in  the  past  considered  of  minor  importance  the  painting  of  iron 
and  steel;  any  paint  that  would  properly  hide  the  surface  of  the 
metal  being  accepted  without  much  question.  The  demand, 
however,  for  structural  steel  for  office  buildings,  factories,  steel 
cars,  railroad  equipment,  etc.,  has  doubled  the  output  of  struc- 
tural paints,  and  created  a  demand  for  painters  having  a  knowl- 
edge of  the  proper  materials  to  use  in  the  painting  of  steel,  so 
that  its  life  may  be  preserved,  and  its  strength  maintained. 
Such  knowledge  is  as  important  to  the  painter  as  a  knowledge 
of  how  to  properly  select  materials  for  the  painting  of  wood,  and 
how  to  temper  these  materials  to  suit  the  various  conditions  met 
with. 

The  Cause  of  Rust.  Everyone  is  familiar  with  the  appearance 
of  rust,  but  few  actually  understand  what  causes  rust.  No 
attempt  will  be  made  here  to  present  even  an  outline  of  the  many 
theories  advanced  to  explain  the  phenomenon  of  the  rusting  of 
iron,  for  the  subject  is  as  diverse  as  it  is  interesting.  A  brief 
resume,  however,  will  be  given  of  the  now  generally  accepted 
theory  that  explains  the  subject.  This  theory  is  called  the  elec- 
trolytic theory.  "  Auto-electrolysis  "  is  the  term  used  to  define 
the  peculiar  tendency  of  iron  to  be  transformed  from  a  metal 
possessing  a  hard  lustrous  surface,  high  tensile  strength,  and 
other  useful  properties,  to  a  crumbling  oxide  that  falls  to  the 
ground  and  again  becomes  part  of  the  earth  from  which  it  was 
originally  taken  by  man. 

This  "  going  back  to  nature  "  is  more  readily  accomplished 
by  most  of  the  steel  produced  to-day  than  by  the  old  hand-made 
irons  produced  many  years  ago.  It  seems  to  be  a  curious  fact 
that  the  more  quickly  a  product  or  an  article  is  fashioned  by 
man,  the  more  quickly  it  tends  to  return  again  to  its  original 

220 


STRUCTURAL    PAINT    TESTS 


221 


_ 


222 


PAINT   TECHNOLOGY  AND   TESTS 


oxidized  condition.  Some  manufacturers  of  steel,  however, 
through  an  understanding  of  the  causes  of  rust,  have  progressed 
in  the  manufacture  of  slow  rusting  materials,  either  by  the 
elimination,  or  by  the  proper  distribution  of  impurities. 

When  iron  is  brought  into  con- 
tact with  moisture,  currents  of 
electricity  flow  over  the  surface  of 
the  iron  between  points  that  are 
relatively  pure  and  points  that 
contain  impurities.  These  currents 
stimulate  the  natural  tendency  of 
the  iron  to  go  into  solution,  and 
the  solution  proceeds  with  vigor 
at  the  positive  points.  The  air 
which  the  water  contains  oxidizes 
the  iron  which  has  gone  into  solu- 
tion, and  precipitates  the  familiar 
brown  iron  rust.  Thus  water, 
which  acts  as  an  acid,  and  air, 
which  acts  as  an  oxidizer,  have 
combined  together  to  accomplish 
the  downfall  of  the  metal. 

Inhibition  and  Stimulation  of 
Rust.  It  is  obvious  that  if  means 
could  be  devised  to  stop  the  solu- 
tion pressure  of  iron  and  make  it 
resistant  to  the  flow  of  surface 
electric  currents,  rust  could  be 
prevented.  Such  methods  have 
been  devised,  and  to  better  illus- 
trate how  they  operate,  an  analogy 
may  be  drawn  between  iron  in 
water  and  shellac  in  alcohol. 

It  is  common  knowledge  that 
when  shellac  is  placed  in  alcohol, 
the  shellac  will  force  itself  into 
solution  in  the  alcohol,  and  form 

Three  Photomicrographs  of         a  clear,   transparent  lacquer.  ^  If, 
Corroding  Steel  however,    there    should    be    mixed 


STRUCTURAL  PAINT  TESTS  223 

with  the  alcohol  a  quantity  of  water,  it  would  be  found  that 
the  shellac  could  no  longer  go  into  solution,  and  it  would  remain 
in  its  original  condition.  In  the  same  way,  if  there  be  placed 
in  water  a  small  quantity  of  material,  such  as  soluble  chromates, 
or  an  alkaline  substance  like  caustic  soda  or  lime,  it  will  be  found 
that  iron  will  no  longer  have  a  tendency  to  go  into  solution  in 
this  treated  water,  but  will  stay  bright  and  clean.  These  mate- 
rials which  prevent  the  rusting  of  iron  have  been  called  by 
Cushman,  who  first  advanced  these  explanations,  "  rust  inhib- 
itors," or  materials  which  inhibit  rusting.  The  paint  maker, 
realizing  the  importance  of  these  rust  inhibitors,  is  incorporating 
them  into  paints  designed  for  the  protection  of  iron  and  steel, 
and  the  success  which  paints  of  this  type  have  met  with  from  a 
practical  standpoint  is  a  justification  of  what  was  first  called 
the  "  electrolytic  theory,"  which  suggested  their  use. 

By  placing  small,  brightly  polished  steel  plates  into  a  mush 
of  paint  pigment  and  water,  a  determination  may  be  made  of 
the  pigment's  effect  upon  the  metal.  Some  pigments,  under 
such  conditions,  cause  rapid  corrosion  of  the  steel  plates.  Such 
pigments  are  stimulators  of  corrosion,  on  account  of  acid 
impurities  which  they  contain,  or  because  of  their  effect  in 
stimulating  galvanic  currents.  Many  carbonaceous  pigments 
are  of  this  type.  Other  pigments  have  the  effect  of  keeping 
bright  the  steel  plates  and  preventing  rust.  Such  'pigments 
are  of  the  inhibitive  type,  and  their  action  is  to  check  or  retard 
the  solution  pressure  of  the  iron. 

The  Effects  of  Moisture.  It  might  occur  to  the  reader  that 
although  paint  pigments,  when  mixed  up  with  water  and  brought 
into  contact  with  the  surface  of  steel,  might  show  either  an  in- 
hibitive or  stimulative  action,  that  it  is  by  no  means  certain  that 
the  same  tendency  will  be  exhibited  by  pigments  when  they  are 
properly  mixed  with  linseed  oil  and  laid  out  as  a  film  upon  the 
surface  of  steel.  In  answer  to  this,  it  may  be  well  to  state  that 
almost  no  material  used  by  mankind  is  absolutely  dry.  Linseed 
oil,  as  it  is  pressed  from  the  seed,  comes  from  the  cells,  carrying 
with  it  a  certain  small  definite  percentage  of  water,  and  it  is 
quite  certain  that  even  the  best  linseed  oil  that  goes  into  use  is 
not  theoretically  dry.  Everyone  knows,  of  course,  that  oil  and 
water  do  not  readily  mix  and  are,  in  fact,  more  or  less  repellent 
to  each  other.  It  is,  however,  true  that,  in  spite  of  this,  oils  can 


224  PAINT   TECHNOLOGY  AND   TESTS 

carry  quite  a  percentage  of  water,  without  the  admixture  being 
apparent  to  the  eye.  In  addition  to  this,  careful  experiments 
have  proved  very  conclusively  that  linseed  oil  films,  even 
after  they  have  oxidized  and  hardened,  have  the  power  to  a 
certain  extent  of  absorbing  water  from  the  atmosphere.  It  is, 
therefore,  safe  to  say  that  no  linseed  oil  film  in  a  paint  coating 
is  dry  all  the  time.  As  a  matter  of  fact,  there  is  abundant  evi- 
dence to  show  that  in  rainy  weather,  and,  in  fact,  when  the 
humidity  in  the  air  is  high,  paint  films  have  absorbed  water. 
As  the  sun  comes  out  and  warms  the  paint  coating,  and  the 
humidity  content  of  the  atmosphere  falls,  this  water  to  a  large 
extent  evaporates  out  of  the  film,  only  to  be  taken  up  again  when 
the  weather  conditions  change.  This  action  may  be  likened 
to  a  breathing  of  the  paint  film,  that  is  to  say,  an  indrawing  of 
water  under  humid  conditions,  followed  by  an  exhaling  of  water 
under  dry  conditions.  With  these  facts  in  mind,  it  must  be 
apparent  that  pigments  laid  out  in  intimate  contact  with  the 
surface  of  steel  are  subjected  at  all  times  either  more  or  less  to 
the  reactions  produced  by  water  contact.  Furthermore,  as  it 
is  a  property  of  water  to  become  saturated  wTith  the  gases  of  the 
atmosphere,  such  as  oxygen,  carbonic  and  sulphurous  acids, 
and  other  impurities,  there  is  present  in  a  protective  paint  film 
at  all  times  the  elements  necessary  to  carry  on  the  corrosive 
process  and  reactions. 

An  outline  of  Cushman's  original  research  work,  upon  which 
has  been  based  the  classification  of  pigments  as  inhibitors, 
stimulators,  and  inerts,  is  clearly  presented  in  his  report 1  as 
Chairman  of  Committee  U  of  the  American  Society  for  Testing 
Materials,  of  which  the  following  is  an  excerpt : 

"  Three  years  ago  the  suggestion  was  made  in  a  paper  pre- 
sented before  the  Tenth  Annual  Meeting  of  this  Society  that  the 
various  types  of  substances  used  as  pigments  in  protective  coat- 
ings might  exert  a  stimulative  or  an  inhibitive  action  on  the  rate 
and  tendency  to  corrosion  of  the  underlying  metal.  It  was 
further  suggested  on  a  theoretical  ground  that  slightly  soluble 
chromates  should  exert  a  protective  action  when  employed  as 
pigments  by  maintaining  the  surface  of  the  iron  in  a  passive 
condition  in  case  water  and  oxygen  penetrated  the  paint  film. 
In  view  also  of  the  well-known  fact  that  alkalies  inhibit  while 

1  Page  73,  1910  Proceedings  of  the  American  Society  for  Testing  Materials. 


*Q*B 


Ferroxyl  Tests  on  Painted  Steel  Surfaces. 
Upper  Row  Painted  with  Stimulative  Paints 
—  Lower  Row  with  Inhibitive  Paints. 


Water  Test  on  Plates  Painted  —  Except  in 
Center  Spot.  Left  Hand  Plates  Painted 
\vith  Stimulative  Paints,  Right  Hand  Plates 
Painted  with  Inhibitive  Paints. 


View  of  Steel  Plates  Painted  with  Stimulative 
Paints,  after  Immersion  in  Ferroxyl  Jelly. 


225 


226  PAINT  TECHNOLOGY  AND   TESTS 

acids  stimulate  the  corrosion  of  iron,  it  was  suggested  that  the 
action  of  more  or  less  pure  pigments  on  iron  in  the  presence  of 
water  should  be  thoroughly  investigated.  Two  years  ago  this 
Committee  invited  the  co-operation  of  Committee  D-l  (then 
known  as  Committee  E)  in  the  investigation,  and  a  special  sub- 
committee representing  the  two  main  committees  was  appointed. 

"  The  methods  and  results  of  the  water-pigment  tests  have 
previously  been  reported  and  published,  and  need  not  be  given 
in  detail.  Briefly,  the  method  consisted  in  immersing  samples 
of  steel  in  water  suspensions  of  the  various  pigments  and  blowing 
air  through  the  containers  for  definite  periods  of  time,  the  corro- 
sion being  measured  by  the  loss  in  weight  sustained  by  the  test 
pieces.  About  fifty  pigments  which  are  in  more  or  less  common 
use  for  painting  steel  were  purchased  in  the  open  market  and  dis- 
tributed among  a  number  of  the  members  of  the  Committee, 
who  agreed  to  carry  out  the  work.  Each  investigator  worked 
independently  of  the  others,  except  that  the  same  general  method 
was  followed;  the  time  of  exposure  to  the  corroding  action, 
however,  varied  in  the  different  experiments.  When  the  results 
were  compared  and  analyzed  by  the  sub-committee,  it  was  felt 
that  the  general  agreement  of  the  results  obtained  by  the  several 
investigators  was  striking  and  merited  further  and  more  system- 
atic work.  As  a  result  of  these  tests  the  sub-committee  ten- 
tatively divided  the  pigments  into  inhibitors,  stimulators, 
and  indeterminates.  The  word  '  indeterminate  '  was  selected 
after  considerable  discussion,  because  the  words  '  neutral  ' 
or  '  inert '  already  possess  a  special  meaning  as  applied  to  paint 
technology.  The  Committee  takes  this  occasion  to  emphati- 
cally state  that  in  adopting  this  tentative  classification,  the  words 
'  inhibitive '  and  '  stimulative '  as  used  by  them  up  to  the 
present  time  apply  only  to  the  results  obtained  in  the  water  tests, 
and  the  inference  that  the  results  obtained  have  decided  which 
class  the  pigment  will  fall  into  when  made  into  a  paint  with  the 
usual  vehicles  and  used  as  a  protective  coating  on  iron  and  steel, 
is  not  justified.  In  order  to  make  this  point  quite  clear,  it  has 
been  agreed  by  the  Committee  to  qualify  the  classification  so 
as  to  speak  of  the  various  materials  tested  as  t  water  stimulative' 
or  '  water  inhibitive.' ' 

Importance  of  Field  Tests.     Although  the  laboratory  accel- 
erated tests  for  the  determination  of  the  relative  value  of  struc- 


STRUCTURAL  PAINT  TESTS 


227 


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228  PAINT  TECHNOLOGY  AND   TESTS 

tural  steel  paints  afford  information  of  some  import,  there  seems 
to  be  a  general  opinion  that  the  best  method  to  follow,  if  informa- 
tion of  a  reliable  character  is  to  be  obtained,  is  to  make  actual 
field  exposure  tests  upon  large  surfaces.  The  results  of  the  above 
described  water-pigment  tests  suggested  the  erection  of  a  series 
of  steel  panels  on  which  to  test  out  the  same  pigments  under 
practical  service  conditions.  The  Paint  Manufacturers'  Asso- 
ciation of  the  United  States  erected  and  painted  the  panels,  the 
work  being  under  the  constant  supervision  of  the  writer,  and 
the  inspection  of  the  work  under  Committee  U  of  the  American 
Society  for  Testing  Materials.  A  brief  resume  of  the  work1  is 
herewith  presented. 

Pickling  and  Preparation  of  Plates.  The  three  types  of 
metal2  selected  for  the  test  were  rolled  to  billets,  the  middle  of 
which  were  selected,  and  worked  up  into  plates  24  inches  wide, 
36  inches  high,  and  J  inch  in  diameter  —  approximately  1 1 
gauge.  A  number  of  plates  of  each  of  the  metals  selected,  in  all 
450,  were  pickled  in  10%  sulphuric  acid,  kept  at  180  to  200  de- 
grees Fahrenheit,  in  order  to  remove  the  mill-scale.  The  plates 
were  then  washed  in  water,  and  later  in  10%  solution  of  caustic 
soda.  Finally  the  plates  were  again  washed  in  water  and  wiped 
dry.  They  were  then  packed  in  boxes  containing  dry  lime,  in 
order  to  prevent  superficial  corrosion.  By  this  method  the  plates 
were  secured  in  perfect  condition,  the  surfaces  being  smooth  and 
free  from  scale.  Upon  these  pickled  plates  paints  were  applied 
with  a  definite  spreading  rate  of  900  square  feet  per  gallon.  The 
unpickled  plates,  coated  with  mill-scale,  were  painted  with  the 
same  paints,  but  without  adopting  any  special  spreading  rate, 
thus  following  more  closely  the  ordinary  method  of  painting 
structural  steel.  A  few  extra  plates  of  special  Bessemer  steel 
and  Swedish  charcoal  iron  were  also  included  in  the  test,  some 
of  which  were  painted,  while  others  were  exposed  without  any 
protective  coating.  Plates  of  the  three  types  of  metal  already 
mentioned  were  also  exposed  unpainted,  both  in  the  black  and 
pickled  condition. 

Fence  Erection  and  Preparation  for  Work.  The  fences  which 
were  erected  for  the  holding  of  the  plates  were  constructed  of 

1  Page  181,  "Corrosion  and  Preservation  of  Iron  and  Steel"  —  Cushman 
and  Gardner  —  McGraw-Hill  Book  Co.,  New  York  City. 

2  Bessemer  Steel,  Open  Hearth  Steel,  and  Pure  Iron. 


230  PAINT   TECHNOLOGY  AND   TESTS 

yellow  pine,  the  posts  being  set  deeply  in  the  ground  and  prop- 
erly braced.  The  framework  of  the  fence  was  open,  with  a  ledge 
upon  the  lateral  girders,  upon  which  the  plates  might  rest,  and 
to  which  the  plates  were  secured  by  the  use  of  steel  buttons. 
After  the  framework  had  been  erected,  painted,  and  made  ready 
for  the  placement  of  the  panels,  a  small  shed  was  built  upon  the 
ground,  and  the  materials  for  the  field  test  placed  therein.  The 
steel  plates  were  unpacked  from  the  boxes  in  which  they  were 
shipped,  brushed  off,  and  stacked  up  ready  for  painting.  Small 
benches  were  erected,  and  the  accessories  of  the  work,  such  as 
cans,  brushes,  pots,  balances,  etc.,  were  placed  in  position. 

Methods  Followed  in  Painting  Plates.  A  frame  resting  upon 
the  workbench  served  to  hold  the  plates  in  a  lateral  position 
while  being  painted,  room  being  allowed  beneath  the  plate  for 
the  operator  to  place  his  hands  in  order  to  lift  the  plates  from 
the  under  surface  after  the  painting  had  been  finished. 

A  pickled  plate  having  been  placed  upon  the  framework 
everything  was  in  readiness  for  the  work.  The  specific  gravity 
and  weight  per  gallon  of  the  paint  to  be  applied  was  determined, 
and  the  amount,  in  grams,  to  be  applied  to  each  individual  panel 
was  calculated  according  to  the  following  formula: 

Spreading  rate  Sq.  ft.  in  plate  Grams  paint  in  gal. 

900  sq.ft.  :  6  ::  4500  :      x 

The  reciprocal  of  x  being  the  number  of  grams  of  paint  to  be 
applied  to  the  panels. 

An  enamel  cup  was  then  filled  with  the  paint  and  a  brush 
well  stirred  within.  The  cup,  paint,  and  brush  were  placed 
upon  the  balances  and  accurately  weighed  in  grams.  After 
most  of  the  paint  had  been  applied  to  the  panel,  cross-brushing  of 
the  panel  was  continued  until  the  pot  with  brush  and  paint 
exactly  counterbalanced  the  deducted  weight.  The  painted 
panel  was  then  set  in  a  rack,  in  a  horizontal  position  to  dry. 

A  period  of  eight  days  elapsed  between  the  drying  of  each 
coat.  The  greatest  care  was  taken  in  the  painting  of  the  edges 
of  the  plates,  and  the  racks  for  containing  the  plates  after  they 
were  painted  were  so  constructed  that  the  paint  would  not  be 
abraded  while  sliding  the  plates  back  and  forth.  The  working 
properties  of  each  paint,  and  the  appearance  of  the  surface  of 
each  plate  after  painting,  were  carefully  noted  and  included  in 


STRUCTURAL  PAINT  TESTS  231 

the  report.  No  reductions  were  made  to  any  of  the  paints 
applied  except  in  three  cases,  where  the  viscosity  was  so  great 
that  it  was  necessary  to  add  a  small  amount  of  pure  spirits  of 
turpentine.  The  amount  of  paint  was  proportionately  increased 
in  such  cases,  so  that  the  evaporation  of  the  turpentine  would 
leave  upon  the  plate  the  amount  of  paint  originally  intended. 

The  appearance  of  the  completed  series  of  test  panels  is  shown 
on  page  221. 

Vehicles  Used  and  Reasons  for  Avoidance  of  Japan  Driers. 
The  pigments  used  were  selected  with  the  view  to  securing  as 
nearly  as  possible  purity  and  strength,  and  as  already  noted, 
were  out  of  the  same  lots  used  in  making  the  preliminary  labora- 
tory tests  on  inhibitives.  They  were  ground  in  a  vehicle  com- 
posed of  two  parts  of  raw  linseed  oil  and  one  part  of  pure  boiled 
oil.  Paint  is. generally  caused  to  dry  rapidly  by  the  use. of  japan 
or  driers.  These  materials  contain  a  large  amount  of  metallic 
oxides  which  might  have  some  effect  in  either  exciting  or  retard- 
ing corrosion.  To  prevent  the  introduction  of  such  a  factor, 
these  materials  were  not  used  in  the  test.  The  boiled  oil,  with 
its  small  percentages  of  metallic  oxides,  was  sufficient,  however, 
to  cause  the  paints  to  dry  in  a  short  time  after  they  were  spread. 

Testing  Effect  of  Various  Prime  Coats.  Some  of  the  special 
tests  made  included  a  series  of  plates  prime-coated  with  differ- 
ent inhibitive  pigments,  and  these  tests  were  designed  to  deter- 
mine which  pigments  offer  the  best  results  for  such  work.  These 
plates  were  all  second-coated  with  the  same  paint.  It  is  the 
opinion  of  the  authors  that  any  good  excluding  paint  may  be 
used  whether  it  be  inhibitive  in  action  or  not,  provided  the  con- 
tact coat  is  inhibitive.  If,  however,  both  coats  can  be  designed 
so  as  to  have  the  maximum  possible  value  from  both  these  points 
of  view,  the  best  results  would,  of  course,  accrue.  The  only  way 
such  data  can  be  obtained  is  by  careful  observation  of  the  results 
of  exposure  tests. 

Combination  Formulas  Tested.  By  selecting  a  series  of  pig- 
ments which  in  the  water  tests  showed  inhibitive  tendencies,  and 
properly  combining  these  pigments  into  a  paint,  it  was  thought 
possible  that  a  more  or  less  inhibitive  paint  would  be  produced. 
If  this  proved  to  be  the  case,  it  would  follow  that  the  selection 
and  introduction  into  a  paint  of  the  stimulative  pigments  would 
inevitably  produce  a  paint  unfit  for  use  on  iron  or  steel. 


232 


PAINT   TECHNOLOGY  AND   TESTS 


Data  on  Application  of  Paints.  The  recorded  data  on  the 
application  of  the  paint  to  the  panels  is  voluminous.  There  is 
presented  herewith,  however,  the  data  on  two  of  the  paints. 

No.  2,  QUICK  PROCESS  WHITE  LEAD: 

Sp.  Gr.  of  pigment 6.78 

Lbs.  to  gallon  oil 20.34 

Sp.  Gr.  of  paint  as  received    2.47 

Wt.  of  paint  per  gallon    20.56 

Grams  to  panel 62 

Condition  of  paint Good 

Working  properties   Works  easy 

Drying 24  hrs.  all  coats 

1  coat          Oct.  26          T  60          B  29.94  W.  fair 

2  coat          Nov.  3  T  54          B  30.23  W.  clear 

3  coat          Nov.  7          T  52          B  29.66  W.  cloudy 

No.  9,  ORANGE  MINERAL  (AMERICAN): 

Sp.  Gr.  of  pigment 8.97 

Lbs.  to  gallon  oil 26.91 

Sp.  Gr.  of  paint  as  received    2.97 

Wt.  of  paint  per  gallon    24.74 

Grams  to  panel 74.7 

Condition  of  paint     Good 

Working  properties    Smooth  —  no  brush  marks 

Drying    Good 

1  coat          Oct.  28          T  58          B  30.01  W.  cloudy 

2  coat          Nov.  4  T  65  B  29.61  W.  cloudy 

3  coat          Nov.  9  T  58          B  29.91  W.  clear 

Composition  of  Paints.  The  following  table  gives  data 
regarding  the  composition,  etc.,  of  paints  applied  to  the  steel 
panels. 

Results  of  Inspection.  The  results  of  an  inspection  of  the 
steel  test  plates,  made  by  Sub-committee  D  representing  Com- 
mittee D-l  of  the  American  Society  for  Testing  Materials,  is 
herewith  presented: 

"  On  Wednesday,  June  28,  1911,  the  second  inspection  of  the 
Atlantic  City  Steel  Test  Panels,  erected  in  October,  1908,  was 
made  by  Sub-committee  D  of  Committee  D-l,  this  Committee 
having  agreed  to  report  upon  the  condition  of  the  painted  sur- 
faces, leaving  any  report  on  the  comparative  corrosion  of  the 
various  types  of  metal  used  in  the  test  to  ^Committee  A-5  on 
the  corrosion  of  iron. 

"  According  to  the  amount  of  rust  apparent  on  the  painted 
surfaces  of  the  panels,  as  well  as  the  degree  of  checking,  chalking, 
scaling,  cracking,  peeling,  loss  of  color,  and  other  signs  of  paint 
failure  shown,  ratings  were  given  each  panel.  The  system  of 


STRUCTURAL  PAINT  TESTS 


233 


Pigment  No.  1 

Name 

Sp.  Gr. 
of  Pig- 
ment 

Wt.  of 
Pigment 
to  Gal. 
of  oil 
Lbs. 

Sp.  Gr. 
of  Paint 
Rec'd 

Wt.  of 
Paint    ; 
per  Gal.  j 
Lbs. 

Grams 
Paint 
to  Panel 
at  900 
Sq.  ft 
spread- 
ing rate 

1 

6.83 

2049 

2.45 

2049 

61  0 

2 
3 

§uick  process  white  lead  

6.78 
5.56 

20.34 
16  68 

2.47 
2.12 

20.34 
16  68 

62.0 
59.0 

4 

Sublimed  white  lead  

6.45 

19.17 

2.36 

19.17 

59.0 

s 

Sublimed  blue  lead                                

6.39 

19  17 

2.42 

19  17 

61.0 

6 

Lithopone    

4.26 

12.78 

1.80 

12.78 

45.3 

7 

Zinc  lead  white                                   

4.42 

13  26 

1.96 

13  26 

49.4 

q 

8  97 

26  91 

2  97 

2691 

74  7 

10 

Red  lead                                              

8.70 

26  10 

2.93 

26  10 

73.6 

12 

Bright  red  oxide  

5.26 

15.78 

2.05 

15.78 

60.0 

14 

Venetian  red  

3.1 

9.30 

1.52 

9.30 

38.0 

15 

3.17 

9  51 

1  50 

9  51 

37  7 

16 

Natural  graphite                           

2.60 

7.80 

1.37 

7.80 

34.4 

17 

Acheson  graphite 

2.21 

6  63 

1  22 

6  63 

30.8 

(  Lampblack    .  .                            

1.82) 

1.82 

\  Barytes    

1.82 

8.92) 

1.60 

8.92 

40.2 

20 

Willow  charcoal                             

1.49 

4.47 

1.08 

4.47 

27.0 

(  Gas  carbon  black  

1.39) 

1.67 

1.39 

\  Natural  barytes 

1.85 

10  03  J 

1003 

507 

24 
27 

French  yellow  ochre  
Natura   barvtes  .                         

2.94 
4.46 

8.82 
13.38 

1.46 

1.83 

8.82 
13.38 

37.0 
46.0 

28 

Precipitated  barvtes  (blanc  fixe) 

4  23 

12  69 

1.84 

12.69 

46.0 

29 

548 

8  22 

1  37 

822 

34  5 

30 
31 

Calcium  carbonate  precipitated  

2.56 
2  33 

7.68 
6  99 

1.35 
1  25 

7.68 
699 

34.0 
31  4 

32 

China  clay  (kaolin)  

2.67 

8.01 

1.34 

8.01 

34.0 

33 
34 
36 

Asbestine  (silicate  of  magnesium)  
American  vermilion  (chrome  scarlet)  .  .  . 

2.75 
6.83 
5  88 

8.25 
20.49 
17  64 

1.38 

8.25 
20.49 
17  64 

34.7 
64.5 
67.1 

39 

Zinc  chromate                                      

3.57 

10.71 

1.57 

10.71 

39.2 

40 

Zinc  and  barium  chromate 

3  45 

10  35 

1  58 

10.35 

40.0 

41 
44 
45 

Chrome  green  (blue  tone)   
Prussian  blue  
Prussian  blue  ...                            

4.44 
1.96 
1.93 

13.32 

5.88 
5.79 

1.94 

13.32 

5.88 
5.79 

49.0 
30.0 
34.5 

48 

Ultramarine  blue  

2.40 

7.20 

1.29 

7.20 

32.5 

49 
51 

Zinc  and  lead  chromate  
Magnetic  black  oxide 

4.76 

14.28 
15.00 

1.92 
1.92 

14.28 
15 

48.3 
48.3 

111 
222 
333 
444 

Composite  Paints 
Brown      Made  from  pigments  that 
Black      ,  were  inhibitive  in  the  water 
White     f  test 
Green     J 

10.82 
10.86 
14.52 
12.77 

i:30 
1.30 
1.74 
1.53 

10.82 
10.86 
14.52 
12.77 

32.7 
32.8 
43.8 
38.6 

555 
666 

777 
888 

Black 
Brown      Made  from  pigments  that 
White       were    stimulative   in    the 
Green       water  te.st 

9.37 
11.74 
14.55 
14.57 

1.125 
1.41 
1.75 
1.75 

9.37 
11.74 
14.55 
14.57 

28. 
35.5 
44. 
14.57 

234 


PAINT  TECHNOLOGY  AND  TESTS 


rating  which  took  into  consideration  all  the  above  conditions, 
was  similar  to  the  system  used  at  the  first  inspection  during  1910, 
when  0  (zero)  recorded  the  worst  results  and  10  (ten)  the  best 
results. 

"  In  Table  No.  1  there  is  shown  the  rating  accorded  by  each 
inspector  to  each  panel,  as  well  as  an  average  for  each  panel. 

TABLE  No.  1.  —  SECOND  INSPECTION  OF  STEEL  PAINT  TEST  PANELS  AT  ATLANTIC  CITY,  N.  J., 
BY  SUB-COMMITTEE  D  OF  COMMITTEE  D-l 


PanelNo. 

Pigment 

W.  H. 

Walker 

P.  H. 

Walker 

H.  A. 

Gardner  ( 
Chair- 
man 

3.  Chap- 
man 

Aver- 
age 

1 

2 

Dutch  process  white  lead    -  

2 
4 

3 

4 

3 
3 

5 
6 

3.7 
4.2 

3 

4 
5 
6 

7 
9 
10 

Zinc  oxide  (XX)    
Sublimed  white  lead  
Sublimed  blue  lead  
Lithopone  
Zinc  lead  white    
Orange  mineral   
Red  lead 

1 
9 
9 
2 
3 
9 
9 

H 
9i 

!t 

9 

9 

1 
9 

r 

5 
9 
9 

2$ 
84. 

1\ 
3^ 
7 
6i 
6* 

1.5 
9.0 

8.8 
2.2 
4.7 
8.3 
8.3 

12 
14 
15 
16 

17 

Bright  red  oxide  
Venetian  red  
Prince's  metallic  brown  
Natural  graphite  
Artificial  graphite  .  . 

81 

5 
6 
5 

9 
9 
7i 

8 

7i 

8 
7 
6 
4 
4 

1 
9 
8 
9J 

8.1 
8.0 
6.3 
6.8 
5.9 

19 

5 

74 

5 

8 

6.3 

20 
21 
24 
27 

Willow  charcoal  
Carbon  black  
Yellow  ochre  (French)  
Barytes  (natural) 

9 
7 
5 
1 

8 
84 

1 

9 
5 
2 
1 

9 

t» 

0 

8.8 
7.2 
5.5 
0.7 

28 
29 
30 
31 
32 
33 
34 
36 
39 

Barytes  (precipitated)  
Calcium  carbonate  (whiting)  
Calcium  carbonate  (precipitated)  . 
Calcium  sulphate  (gypsum)  
China  clay  (kaolin)  
Asbestine  (magnes.  silicate)  
American  vermilion  .  .  .  .  •  
Lead  chromate  
Zinc  chromate  .  ... 

2 
0 
0 
1 
6 
5 
10 
7 
9 

V 
0 

1 

6 
4* 

10 

1\ 
9 

2 
0 
0 
1 
7 
6 
10 
8* 
10 

2 
0 
0 
3 
6i 
5 
10 
8 
9£ 

1.8 
0.0 
0.0 
1.7 
6.3 
5.1 
10.0 
7.7 
9.5 

40 
41 
44 
45 

Zinc  and  barium  chromate  
Chrome  green  (blue  tone)  
Prussian  blue,  W.  S  
Prussian  blue,  W.  I.  ... 

9 
10 
9 

8 

9i 

10 
9* 
9* 

10 
10 
94. 

8^ 

9* 

9^ 
9 
84. 

9.5 

9.8 
9.0 
8.5 

48 
49 
51 
111 
222 

Ultramarine  blue  
Zinc  and  lead  chromate  
Magnetic  black  oxide  
Brown  composite  paint  
Black  composite  paint 

0 

10 
9 

7 
9 

0 
9i 

8* 

9 

0 
10 
10 
9 
9 

0 

9| 

S1 

84 

0.0 
9.7 
9.5 
8.5 

8.8 

3333 
444 

White  composite  paint  

4 
5 

4 

7 

7 
7 

32 

8 

4.5 

6.7 

555 
666 

Black  composite  paint  
Brown  composite  paint 

9 

8 

9 

8 

6 
6 

9 
9 

8.2 

7.7 

777 
888 

White  composite  paint  

7 
7 

10 

8 

5 

8 

7 
9 

7.2 

8.0 

2000 

3000 
4000 

100 

1  coat  zinc  chromate    
1  coat  iron  oxide  excluder   
1  coat  lead  chromate  
1  coat  red  lead                         ) 
1  coat  iron  oxide  excluder  ) 
Straight   carbon   black    paint   with 
turps  and  drier 

8 

7 
7 

5 

8£ 

8 
8^ 

8| 

8 

7 
8 

4 

8 

7^ 
7i 

8} 

8.1 

7.3 

7.7 

6.5 

90 

Straight  lampblack  paint  with  turps 
and  drier 

5 

7 

3 

8 

5.7 

5555 
1000 
1  plate 

Coal  tar  paint  over  red  lead    
Chrome  resinate  in  oil  (1  coat)  .  .  . 
3  coats  boiled  linseed  oil 

4 
1 
1 

8 
0 
0 

2 
0 
1 

7 
2 
4 

5.2 
0.7 
1.5 

STRUCTURAL  PAINT  TESTS 


235 


"  In  Table  No.  2  there  is  shown  the  rating  obtained  by  those 
panels  which  were  considered  by  the  committee  as  meriting 
from  8  to  10,  and  having  given  the  best  all-round  service. 

TABLE   No.  2.  —  ANALYSIS  OF  AVERAGES.     GRADE  OF  EXCELLENCE  FROM 

8  TO  10 


Plate 

Pigment 

Average 

34 

American  vermilion  (basic  chromate  of  lead)  . 

10.0 

41 

Chrome  green                                               .            .... 

9.8 

49 

Lead  and  zinc  chromate  

9.7 

39 

Zinc  chromate     

9.5 

40 

Zinc  and  barium  chromate 

9.5 

51 

Black  oxide  of  iron 

9.5 

4 

Sublimed  white  lead                                                  .... 

9.0 

44 

Prussian  blue                                     .  .           

9.0 

5 

Sublimed  blue  lead    

8.8 

20 

Willow  charcoal   

8.8 

222 

Composite  paint 

8.8 

45 

Prussian  blue 

8.5 

111 

Composite  formula 

8.5 

9 

Orange  mineral                                                              .  . 

8.3 

10 

Red  lead 

8.3 

555 

Composite  paint                                                  

8.2 

12 

Bright  red  oxide  of  iron    .                  

8.1 

2000 

1  coat  zinc  chromate;  1  coat  iron  oxide  

8.1 

14 

Venetian  red  

8.0 

888 

Composite  paint 

8.0 

Comparison  of  Results.  It  is  of  interest  to  compare  with 
Table  2  of  the  above  report,  Table  2  of  the  1910  report  of 
Committee  U  of  the  American  Society  for  Testing  Materials. 
Both  charts  show  the  highly  inhibitive  pigments  to  be  in  the 
lead. 


236 


PAINT  TECHNOLOGY  AND  TESTS 


COMMITTEE  U  REPORT   1910 
TABLE  II.  —  ANALYSIS  OF  AVERAGES.     GRADE  OF  EXCELLENCE  FROM  8  TO  10 

(Only  resistance  to  corrosion  was  considered,  and  only  pigments  which  were  com- 


mon to  both  tests  are  incl 


ny  p 
uded) 


No. 

Pigment 

Average 

34 

American  vermilion  (chrome  scarlet) 

98 

41 

Chrome  green  (blue  tone)    

97 

40 

Zinc  and  barium  chromate  

97 

5 

Sublimed  blue  lead    

96 

4 

Sublimed  white  lead 

9  5 

49 
39 

Zinc  and  lead  chromate    
Zinc  chromate    . 

9.5 
94 

12 

Bright  red  oxide 

9  3 

44 
16 

Prussian  blue  (water  stimulative)  
Natural  graphite    . 

9.2 
9  1 

9 

Orange  mineral  (American) 

9  0 

36 

Medium  chrome  yellow    . 

90 

2 

White  lead  (quick  process)  . 

89 

20 

Willow  charcoal   

88 

45 

Prussian  blue  (water  inhibitive)    . 

88 

1 

W'hite  lead  (Dutch  process)  

87 

10 

Red  lead    

87 

7 

Zinc  lead  white  

8.0 

The  writer  has  recently  made  a  careful  inspection  of  the  panels 
painted  with  single  pigment  paints,  and  has  made  the  following 
brief  summary  of  the  characteristic  appearance  of  each. 

Panel  No.  i  —  Dutch  Process  White  Lead.  The  excessive 
chalking  which  took  place  began  to  disappear  at  the  end  of  a 
year,  being  washed  away  by  the  rains  and  carried  away  by  the 
winds,  so  that  there  was  left  upon  the  surface  but  a  thin  coating 
of  pigment,  insufficient  to  give  good  protection.  Slight  corro- 
sion was  apparent  beneath  the  film. 

Panel  No.  2  —  Quick  Process  White  Lead.  In  the  same 
condition  as  Panel  No.  1. 

Panel  No.  3 — Zinc  Oxide.  Panel  covered  with  thin  lateral 
streaks  of  rust,  due  to  the  admittance  of  moisture  in  cracks 
caused  by  brittleness  of  film.  Result  doubtless  due  to  insuffi- 
cient amount  of  oil  used  with  pigment.  Removal  of  film  shows 
steel  very  bright  except  where  cracks  have  formed. 

Panel  No.  4  —  Sublimed  White  Lead.  Although  sublimed 
white  lead  chalked  very  heavily,  the  chalked  pigment  seemed  to 


STRUCTURAL  PAINT  TESTS  237 

be  tenacious  and  adhered  to  the  plate,  presenting  an  excellent 
surface  with  absence  of  rust.  Film  of  good  color  and  quite 
elastic. 

Panel  No.  5  —  Sublimed  Blue  Lead.  In  same  condition  as 
Panel  No.  4,  but  color  has  slightly  faded. 

Panel  No.  6  —  Lithopones.  Lithopone  was  early  destroyed, 
as  is  usual  with  this  pigment  when  used  alone  on  exterior  sur- 
faces. It  became  rough  and  discolored,  presenting  a  very 
blotchy  appearance  and  disclosed  the  formation  of  rust  working 
through  the  film. 

Panel  No.  7  —  Zinc  Lead  White.  In  general  good  condition 
with  the  exception  of  the  color,  which  is  slightly  dark.  Medium 
chalking  was  apparent  but  only  very  slight  corrosion  appeared. 

Panel  No.  9  —  Orange  Mineral.  In  excellent  condition, 
showing  a  good  firm  surface  with  no  checking  or  corrosion  appar- 
ent. Shortly  after  exposure  the  film  became  covered  with  a 
white  coating  of  carbonate  of  lead,  which  indicates  action  of  the 
red  lead  with  the  carbonic  acid  of  the  atmosphere.  Removal  of 
this  white  coating  with  water  discloses  the  brilliant  color  of  the 
unaffected  portion  of  the  red  lead. 

Panel  No.  10  —  Red  Lead.     In  same  condition  as  Panel  No.  9. 

Panel  No.  12  —  Bright  Red  Iron  Oxide.  In  general  good  con- 
dition. Film  intact  and  unfading  in  color. 

Panel  No.  14  —  Venetian  Red.  Similar  to  Panel  No.  12,  but 
slight  corrosion  apparent  beneath,  in  localized  spots,  and  film 
showing  slight  wart-like  formations. 

Panel  No.  15  —  Prince's  Metallic  Brown.  Similar  to  Panel 
No.  14. 

Panel  No.  16  —  Natural  Graphite.  Deeply  pitted  in  spots, 
showing  bulbous  eruptions,  indicating  the  stimulative  nature  of 
this  pigment. 

Panel  No.  17 —  Artificial  Graphite.  In  same  condition  as 
Panel  No.  16. 

Panel  No.  19  —  Lampblack  and  Barytes.  Although  the  film 
seems  to  be  intact,  there  are  apparent  abrasions  of  the  surface 
showing  stimulative  corrosion  effects  of  a  pronounced  nature. 

Panel  No.  21  —  Carbon  Black  and  Barytes.  In  same  con- 
dition as  Panel  No.  19. 

The  longevity  of  lampblack  and  carbon  black  paint  films  when 
applied  to  wood  has  been  attributed  to  the  slow  drying  nature 


238         PAINT  TECHNOLOGY  AND  TESTS 


\ 


Corrosion  Pits  on  Graphite  Panel 


STRUCTURAL    PAINT    TESTS 


239 


Rust  on  Stripped  Graphite  Film 


240 


PAINT  TECHNOLOGY  AND   TESTS 


STRUCTURAL  PAINT  TESTS 


241 


of  these  pigments  when  mixed  with  oil.  It  is  assumed  that  they 
have  the  property  of  keeping  the  oil  in  a  semi-drying  condition, 
which  will  not  disintegrate  as  early  as  when  the  oil  is  thoroughly 
dried  to  linoxyn.  If  this  is  true,  it  would  seem  advisable  to  use 
with  hard-drying  pigments,  a  proportion  of  some  oil  that  is  semi- 


Corroded  and  Pitted  Surface  of  Plate  Painted  with  Stimulative 

Paint 


drying  in  nature  or  one  which  will  leave  a  film  not  too  hard. 
Soya  bean  oil,  wood  oil,  and  fish  oil  present  themselves  as  can- 
didates for  such  use.  How  they  will  work  in  practice,  however, 
is  a  question  not  yet  determined.  On  the  other  hand,  it  is  well 
known  that  these  pigments  require  enormous  quantities  of  oil 
in  order  to  grind  to  a  working  consistency,  and  it  is  possible  that 


242  PAINT  TECHNOLOGY  AND   TESTS 

the  life  of  such  coatings  is  due  rather  to  the  property  of  these 
pigments,  of  taking  up  large  quantities  of  oil,  than  to  their  effect 
upon  the  slow  drying  of  oil.  Excessive  oil  carrying,  however, 
should  be  avoided,  as  shown  by  the  early  failure  and  pitting  of 
those  carbon  black  and  lampblack  paints  ground  with  very 
large  quantities  of  oil,  as  is  the  usual  practice.  When  these  car- 
bon and  lampblack  pigments  were  ground  with  barytes  (which 
is  a  heavy  pigment  and  requires  only  about  9  pounds  of  oil  to 
100  pounds  of  pigment,  as  against  175  pounds  of  oil  to  100 
pounds  of  lampblack),  it  was  found  that  the  lampblack  and  car- 
bon black  paints  were  reinforced  and  made  more  suitable  for 
actual  practice.  The  stimulative  nature  of  these  black  pig- 
ments, however,  asserted  itself  in  both  cases,  and  large  pittings 
and  eruptions  were  evident  at  the  end  of  a  year.  Carbon  black, 
lampblack,  graphite,  or  any  other  good  conductor  of  electricity 
should  never  be  placed  next  to  the  surface  of  iron.  They  are 
good  as  top-coatings,  but  not  as  prime-coaters.  Some  pigments 
are  stimulators  of  corrosion,  because  they  contain  water-soluble 
impurities  that  hasten  the  rusting,  while  others,  like  graphite, 
hasten  it  simply  because,  being  good  conductors,  they  stimulate 
surface  electrolysis. 

Panel  No.  20  —  Willow  Charcoal.  In  excellent  condition 
throughout.  Presence  of  small  quantities  of  potash  may  be 
responsible  for  the  inhibitive  nature  of  this  black  pigment. 

Panel  No.  24  —  Ochre.  While  the  film  seems  intact,  it  has  a 
very  mottled  appearance  and  examination  shows  eruptions  of 
rust  through  the  film,  in  several  places. 

Panel  No.  27  —  Natural  Barytes.  Within  a  year  the  film 
became  pin-holed,  and  corrosion  was  apparent.  At  the  end  of 
three  years  very  little  of  the  pigment  was  left  upon  the  plate, 
having  chalked  and  scaled  off.  Barytes  has  proved  its  useful- 
ness as  a  constituent  of  a  combination  type  of  paint,  but  it 
should  not  be  used  alone. 

Panel  No.  28  —  Blanc  Fixe.  In  the  same  condition  as  Panel 
No.  27,  but  slightly  more  chalking  and  disintegration  was 
shown. 

Panel  No.  29  —  Whiting.  Plates  coated  with  calcium  car- 
bonate or  whiting  in  oil  presented  a  very  fair  appearance  at  the 
start  of  the  test,  but  they  soon  began  to  chalk  and  disintegrate. 
It  is  well  known  that  whiting,  being  alkaline,  has  the  property 


STRUCTURAL  PAINT  TESTS 


243 


Panel  Painted  with  Blanc  Fixe.     Right  Side  Stripped  of  Paint  to 
Show  Corrosion 


244 


PAINT   TECHNOLOGY  AND   TESTS 


Scaled  Whiting  Films 

Chemically  Active  Pigments  and  Their  Effect  After  Eighteen  Months'  Wear 


STRUCTURAL  PAINT  TESTS 


245 


of  acting  on  oil  and  causing  its  early  disintegration  by  saponifica- 
tion.  As  a  matter  of  fact,  six  months  after  the  whiting  plates 
were  exposed,  crumbling  of  the  surface  appeared,  and  twelve 
months  was  sufficient  for  the  total  destruction  of  the  paint.  At 
this  time  the  rusted  surface  of  the  plates  which  had  been  painted 
with  calcium  carbonate,  seemed  not  to  rust  as  fast  as  those 
plates  which  were  exposed  without  paint  coatings,  and  the  rust 


Plate  Showing  Effect  of  Chemically  Active  Pigments  on  Oil 
after  One  Year's  Wear 

which  had  formed  appeared  to  be  of  an  even,  fine  texture.  On 
the  lower  left-hand  corner  of  these  plates  had  been  lettered  the 
figures  "  29  "  and  "  30,"  using  lampblack  in  oil.  One  of  the 
most  remarkable  things  which  appears  on  the  fence  to-day  is 
the  perfect  condition  of  these  lampblack  letters  over  their  prim- 
ing coat  of  calcium  carbonate,  standing  out  in  clear  relief  against 
the  rusted  metal.  This  test  would  suggest,  therefore,  that  if 
the  surface  of  metal  is  properly  protected  with  a  pigment  which 


246  PAINT  TECHNOLOGY  AND   TESTS 

is  slightly  alkaline  or  inhibitive  in  nature,  and  then  topped  with 
a  good  weather-resisting  material,  such  as  lampblack,  graphite 
or  carbon  black,  good  results  would  be  obtained.  Further  tests 
will  be  made  to  determine  the  value  of  this  suggestion. 

Panel   No.    30  —  Precipitated   Calcium   Carbonate.     Showed 
more  rapid  destruction  than  Panel  No.  29. 


Corrosion  Adhering  to  Film  Stripped  from  Panel   Painted 
with  Gypsum  (Calcium  Sulphate) 

Panel  No.  31  —  Calcium  Sulphate.  Under  the  paint  film  of 
gypsum,  rust  soon  appeared,  showing  that  the  film  was  not  a 
good  excluder  of  moisture.  Although  the  film  remained  intact, 
rusting  progressed  throughout  the  test  and  considerably  dark- 
ened the  color  of  the  paint. 

Panel  No.  32  —  China  Clay.  This  pigment  gave  excellent 
service  for  eighteen  months.  Afterwards  indications  of  corrosion 
were  shown,  and  apparent  breakdown  of  the  film  was  indicated. 


STRUCTURAL   PAIXT   TESTS 


217 


China  Clay 


Asbestine 


Gypsum 


248 


PAINT  TECHNOLOGY  AND   TESTS 


Panel  No.  33  —  Asbestine.  In  the  same  condition  as  Panel 
No.  32. 

Panel  No.  34  —  American  Vermilion.  This  pigment  has 
given  perfect  protection  to  the  plates.  The  film  is  strong  and 
elastic,  and  upon  removal  reveals  the  bright  steel.  No  chalk- 
ing, checking,  discoloration,  or  other  signs  of  paint  failure  are 


Excellent    Surface    shown    by   American    Vermilion    after   nearly 
Four  Years'  Exposure 

shown.  It  would  appear  that  the  inhibitive  characteristics  of 
this  pigment  are  pronounced,  and  it  promises  to  give  efficient 
service  for  several  years  more. 

Panel  No.  36  —  Lead  Chromate.     This  panel  is  in  generally 
fair  condition,  but  slight  checking  is  shown. 


STRUCTURAL  PAINT  TESTS 


249 


Perfect  Condition  of  Plate  Painted  with  Zinc  Chromate;  One  Half 
Stripped.     (Negative  cracked} 


250  PAINT  TECHNOLOGY  AND   TESTS 

Panel  No.  39  —  Zinc  Chromate.  This  panel  is  in  condition 
similar  to  Panel  No.  34,  presenting  a  perfect  appearance,  with 
decided  maintenance  of  color,  elasticity  of  film,  and  freedom  from 
any  bad  characteristics.  It  has  proved  to  be  one  of  the  highest 
type  rust  inhibitive  pigments. 

Panel  No.  40  —  Zinc-and-Barium-Chromate.  Although  the 
color  of  this  pigment  is  not  very  pleasing,  it  has  proved  itself  to 
be  the  equal  of  zinc  chromate  in  its  protective  value. 

Panel  No.  41  —  Chrome  Green.  In  excellent  condition. 
Presents  an  appearance  similar  to  Panels  Nos.  34  and  39. 
Its  surface  is  perfect  and  will  doubtless  give  service  for  many 
years. 

Panel  No.  44  —  Prussian  Blue.  This  panel  stands  forth  as  the 
most  wonderful  moisture-excluder  in  the  whole  test,  its  sur- 
face presenting  an  appearance  similar  to  a  varnished  plate,  even 
after  three  years'  exposure.  Action  between  the  pigment  and  the 
oil,  resulting  in  the  formation  of  iron  linoleate,  may  account  for 
this  property. 

Panel  No.  45  —  Prussian  Blue.  In  same  condition  as  Panel 
No.  44. 

Panel  No.  48  —  Ultramarine  Blue.  Soon  after  this  test  was 
exposed,  early  vehicle  decay  and  excessive  chalking  were  observed. 
The  admittance  of  moisture  may  have  caused  the  formation  of 
acid  with  the  sulphur  content  of  the  pigment,  -which  would 
account  for  the  rapid  corrosion  which  followed,  ft  is  of  a  pro- 
nounced stimulative  type.  The  effect  of  stimulative  under- 
coatings  is  well  shown  on  some  special  plates  on  thf-fence,  which 
when  received  were  not  pickled  before  painting,  but  had  upon 
their  surfaces  the  ordinary  coating  of  mill  scale.  Over  this  had 
been  stencilled  in  a  triangular  form  the  trade  mark  of  the  manu- 
facturer. The  stencilling  material  was  made  of  ultramarine 
blue.  When  these  plates  were  painted  with  some  of  the  special 
paints,  and  exposed,  the  stimulative  nature  of  the  ultramarine 
blue  began  to  assert  itself,  and  within  a  short  time,  wherever  the 
stencil  marks  were  located,  signs  of  rust  began  to  appear  through 
the  coatings  of  top  paint  which  had  been  applied.  Corrosion 
under  these  stencil  marks  became  so  great  that  the  trade  mark 
was  plainly  outlined  in  letters  of  rust.  This  would  seem  to  be 
final  proof  that  pigments  of  a  stimulative  nature  should  never  be 
used  for  the  priming  of  iron  and  steel. 


STRUCTURAL  PAINT  TESTS  251 

Panel  No.  49  —  Zinc-Lead  Chromate.  In  excellent  condition 
throughout,  with  a  smooth  surface  and  showing  no  corrosion. 
Stands  in  the  same  class  as  Panels  Nos.  34  and  39. 


Effect  of  Stimulative  Paint.  Manufacturer's  Trade  Mark 
Stencilled  on  Bare  Metal  in  Triangular  Form,  showing 
Through  Subsequent  Paint  Coating 

Panel  No.  51  —  Black  Magnetic  Oxide  of  Iron.     In  excellent 
condition. 


CHAPTER  XVII 
THE   SANITARY  VALUE   OF  WALL  PAINTS 

Decoration  and  Sanitation.  The  proper  decoration  of  the 
interior  of  dwellings  and  public  buildings  has  become  of  even 
greater  importance  than  the  protection  and  decoration  of  ex- 
teriors. There  is,  moreover,  an  increasing  demand  for  har- 
monious effects  and  the  production  of  more  sanitary  conditions 
than  have  prevailed  in  the  past.  Up  until  a  few  years  ago  a 
great  variety  of  wall  papers  of  more  or  less  pleasing  appear- 
ance were  almost  exclusively  used  for  the  decoration  of  walls 
in  the  interior  of  buildings,  and  their  application  was  com- 
monly considered  the  most  effective  means  of  wall  decora- 
tion. There  seems  to  be  no  question,  however,  that  the  use  of 
wall  paper  is  steadily  decreasing,  and  that  the  art  of  interior 
decoration  is  undergoing  a  transition  to  the  almost  universal  use 
of  paint. 

Modern  progress  demands  the  maintenance  of  sanitary  con- 
ditions for  the  benefit  of  the  public  welfare,  and  there  is  no  doubt 
that  from  the  standpoint  of  sanitation  and  hygiene,  properly 
painted  wall  surfaces  are  far  superior  to  papered  walls.  There 
is  an  abundance  of  evidence  which  shows  that  dust  germs  may 
easily  be  harbored,  and  thus  disease  transmitted  from  wall 
paper.  In  the  tenement  houses,  which  are  common  to  the  larger 
cities,  and  to  a  lesser  extent  in  the  dwellings  found  in  smaller 
communities,  where  tenants  are  more  or  less  transient,  the  con- 
tinued maintenance  of  sanitary  conditions  presents  a  difficult 
problem.  Infectious  and  epidemic  illnesses  generally  leave  be- 
hind bacilli  of  different  types,  which  may  find  a  culture  medium 
in  the  fibrous  and  porous  surfaces  presented  by  wall  paper, 
backed  up  as  they  invariably  must  be  by  starch,  casein,  or  other 
organic  pastes.  Occasionally  the  restrictions  of  local  boards  of 
health  provide  in  such  events  for  proper  fumigation,  but  too 
often  no  precautions  are  taken  to  destroy  the  disease  germs 

252 


SANITARY  VALUE  OF  WALL  PAINTS 


253 


P 


254         PAINT  TECHNOLOGY  AND  TESTS 

which  are  caught  in  the  dust  which  collects  on  wall  paper.  As  a 
rule,  both  tenant  and  landlord  are  oblivious  to  all  conditions 
which  cannot  be  readily  seen  or  detected.  Burning  sulphur,  one 
of  the  most  effective  means  of  fumigation,  will  generally  cause 
bleaching  and  consequent  fading  of  the  delicate  colors  used  in 
printing  the  designs  upon  wall  paper.  Washing  of  the  paper  with 
antiseptic  solutions  will  destroy  its  adhesiveness  to  the  plaster 
and  often  cause  bulging  and  general  destruction. 

Hospital  Practice.  In  hospitals,  where  it  is  necessary  to 
maintain  sanitary  conditions,  the  walls  are  invariably  painted, 
and  requirements  should  demand  the  use  of  paints  which  can 
be  washed  frequently,  so  that  there  will  be  no  possibility  of 
uncleanliness.  Inquiry  made  of  a  prominent  surgeon 1  connected 
with  one  of  the  large  metropolitan  hospitals  substantiated  the 
writer's  findings  regarding  the  greater  sanitary  value  of  wall 
paints,  and  brought  forth  the  information  that  in  hospitals 
under  construction  provision  had  been  made  for  the  finishing  of 
walls  so  that  a  hard,  non-absorbent,  and  washable  surface  might 
be  obtained.  The  same  authority  stated  that  the  common 
practice,  in  apartments  and  tenements,  of  covering  the  old  wall 
paper  over  with  a  layer  of  new  each  time  a  tenant  moved  in, 
should  be  condemned,  and  that  from  a  hygienic  standpoint  the 
use  of  sanitary  wall  paints  should  be  advocated  in  all  dwellings 
as  well  as  public  buildings. 

If  such  conditions  are  maintained  in  hospitals,  where  spe- 
cial attention  is  paid  to  sanitation,  it  would  appear  that  similar 
precautions  should  be  equally  as  necessary  in  public  build- 
ings and  in  dwellings  —  wherever,  in  fact,  people  congregate 
or  live. 

Sanitary  Wall  Paints.  There  have  recently  appeared  in  trade 
a  number  of  wall  paints  composed  of  non-poisonous  pigments 
ground  in  paint  vehicles  having  valuable  waterproofing  and 
binding  properties,  and  of  a  nature  to  produce  the  flat  or 
semi-flat  finish  that  has  become  so  popular.  Such  paints 
produce  a  sanitary,  waterproof  surface,  which  permits  of  fre- 
quent washing.  By  their  use  it  is  possible  to  secure  a  more  per- 
manent and  a  wider  range  of  tints  than  can  be  obtained  with 
wall  paper,  as  they  are  produced  in  a  myriad  of  shades,  tints  and 
solid  colors,  from  which  any  desired  combination  may  be  selected, 
^r.  F.  F.  Gwyer,  Cornell  Uni.  Med.  Col.,  New  York  City. 


SANITARY   VALUE  OF  WALL  PAINTS  255 

On  the  border  or  on  the  body  of  walls  decorated  with  such  paints, 
attractive  stencil  designs,  which  bring  out  in  relief  the  color 
combinations,  may  be  applied. 

For  the  decoration  of  chambers  and  living  rooms,  delicate 
French  grays,  light  buffs,  cream  tints  and  ivory  whites  may  be 
used,  while  in  the  library  and  other  rooms  richer  and  more  solid 
colors,  such  as  greens,  reds,  and  blues,  may  be  harmoniously 
combined. 

Defects  of  Wall  Paper.  It  recently  occurred  to  the  writer  to 
investigate  the  conditions  which  obtain  in  many  apartment 
houses  in  the  larger  cities.  Inspection  of  a  number  of  such 
places,  in  which  wall  paper  had  been  exclusively  used  on  the 
walls,  showed  generally  bad  conditions;  bulging  of  the  surfaces, 
caused  by  dampness  in  the  walls,  which  had  loosened  up  the 
binder,  as  well  as  peeling  and  dropping  of  the  paper  from  the 
ceilings,  were  frequently  observed.  In  many  cases  a  shabby 
appearance  was  shown,  accompanied  by  an  odor  which  suggested 
decomposition  of  the  paste  binder  used  on  the  paper.  The  writer 
was  impressed  with  the  fact  that  such  conditions  could  easily  be 
avoided  by  the  very  simple  expedient  of  using  properly  manu- 
factured wall  paints,  which  are  so  easily  made  dustproof  and 
waterproof. 

Samples  of  wall  paper,  which  had  been  applied  to  plastered 
walls  for  a  year  or  more,  were  obtained,  and  examination  under 
the  microscope  showed  a  most  uncleanly  surface.  Cultures  were 
made  of  these  samples,  and  bacilli  of  different  types  were  de- 
veloped in  the  culture  medium  in  a  short  time. 

Experimental  Evidence.  That  the  above  conditions  could  not 
have  existed,  had  proper  wall  paints  been  used,  seemed  doubt- 
less, and  suggested  a  carefully  conducted  experiment  to  prove  the 
relative  sanitary  values  of  wall  paper  and  wall  paints.  A  large 
sheet  of  fibre  board,  such  as  is  occasionally  used  to  replace 
plastered  walls,  was  painted  on  one  side  with  a  high-grade  wall 
paint,  three-coat  work.  A  similar  sheet  was  papered  on  one 
side  with  a  clean,  new  wall  paper.  These  test  panels  were  placed 
where  unsanitary  conditions,  such  as  dampness,  foul  odors,  and 
a  scarcity  of  air  were  present.  After  a  short  period  of  exposure, 
the  panels  were  taken  to  the  bacteriological  laboratory  and  a 
small  section  of  the  painted  surface,  about  two  inches  square,  as 
well  as  a  small  section  of  the  papered  surface  of  similar  size,  were 


256  PAINT  TECHNOLOGY  AND   TESTS 

removed  and  used  for  making  cultures.  In  each  case  the  sur- 
face of  the  section  under  test  was  washed  with  100  c.c.  of  dis- 
tilled, sterilized  water.  The  washings  which  dripped  from  the 
surface  were  collected  in  a  graduated  flask.  One  c.c.  of  the 
washings  was  used  in  each  case,  admixed  with  bouillon  and  again 
with  agar-agar.  The  enormous  development  of  bacteria  in  the 
bouillon,  treated  with  the  washings  from  the  wall-papered  sur- 
face, was  sufficient  evidence  to  convince  one  of  the  greater 


I 


DEVELOPMENT  OF  BACTERIA  IN  BOUILLON  SOLUTIONS 

Note  Practical  Freedom  of  Note  Milky  Appearance  of 
Bacteria  in  Clear  Bouillon  Solution  Due  to  Heavy  De- 
Solution  Treated  with  velopment  of  Bacteria  in 
Washings  from  Sanitary  Bouillon  Treated  with 
Wall  Paint  Washings  from  Wall  Paper 

sanitary  value  of  the  wall  paint,  the  washings  from  which  gave 
a  culture  practically  free  from  bacteria.  The  colonies  of  bac- 
teria shown  in  the  petri-dish  test  made  of  the  washings  from 
wall  paper  further  supports  these  findings.  It  will  be  noticed 
that  the  tests  made  from  the  washings  of  the  wall  paint  show 
practical  absence  of  bacteria,  and  was  clear,  as  was  the  bouillon- 
solution  test  of  the  paint.  The  washings  from  the  wall  paper 
showed  active  development  of  bacteria,  both  in  the  bouillon  and 
agar  tests. 


SANITARY  VALUE  OF  WALL  PAINTS  257 

From  the  Conservation  Standpoint:  It  would  be  of  interest  to 
sum  up  in  figures  the  acreage  and  cordage  of  wood  that  annually 
is  transformed  into  pulp  for  the  manufacture  of  wall  paper. 
Unfortunately,  there  are  no  available  statistics  on  this  subject. 
It  is  clear,  however,  that  from  the  standpoint  of  conservation 
the  use  of  wall  paints  should  take  precedence  over  the  use  of 
wall  paper. 


INDEX 

PAGE 

Abrasion,  apparatus  for  determinating  resistance  to,  153 

Acid  reacting  compounds, 215 

Actinic    light    tests,    112 

Adhesive  power  of  Paint  Coating,  104 

Aluminum    Silicate,    62 

American  Vermilion,       64 

Analogies  of  Paint  and  Concrete  manufacture, 94 

Analyses  of  Averages  in  Atlantic  City  steel  paint  test,   235,  236 

Corn  Oil, 16 

Cottonseed  Oil, 15 

Derbloomed  Mineral  Paint  Oil, 18 

Iron  Oxide  Pigments,  table, 63 

Linseed  Oil, 7 

Menhaden   Oil, ...... . . . 14 

Oils  used  in  Washington  tests, 211 

Petroleum     Spirits,     20 

Rosin    Oil,    16 

Soya  Bean  Oil,    8 

Sunflower    Oil,     15 

Tung    Oil,     12 

Whale  Oil, ,..,..  .".'.I. ."...,....''. :.'...; 14 

Wood    Turpentine,     19 

Asbestine,      ...  /. 55 

Atlantic  City  fence  tests,  107 

steel  paint  tests, 228-235 

Checking, 122 

Gloss, 122 

Hiding    power,     122 

inspection  of,   114 

Methods   used,    114 

Results, 124 

Auto-electrolysis,     220 

Bacteria  in  wall  paper,    256 

Barium  Sulphate,    55 

Barytes,     55 

and  Silica  Paints  in  Pittsburg  tests. 172 

Basic   Carbonate- White   Lead,     42 

Benzine,     20 

Benzol, 20 

259 


260  INDEX 

PAGE 

Blanc  Fixe,   60 

Blue  Lead,  Sublimed, 47 

Blue  Paint  for  concrete  wall,  formula,   215 

Blue  paints  in  Pittsburg  tests, 142 

Boiled   Linseed   Oil, 2 

Driers  in, 28 

Bone  Black,      66 

Calcium  Carbonate,  60 

Calcium  Sulphate,  60 

Carbon  Black,  66 

Cause  of  rust  in  steel  work, 220 

Chalking  test  for  laboratory, 149 

Checking  and  cracking  in  Pittsburg  tests, • 166 

Checking,  in  Atlantic  City  tests,  122 

China  Clay,  62 

Chrome  Green, 66 

Chrome  Yellow,  64 

Coatings  for  cement  and  concrete,  214 

Colored  formulas  in  North  Dakota  tests, 190 

Colors,  report  of,  in  Pittsburg  tests, 139 

Combination  formulas  in  inhibitive  paints,  231 

Composite  formulas  in  North  Dakota  tests, 190 

in  Pittsburg  tests,  142 

Composition  of  paints,  in  steel  test,  232 

Conclusion  from  Pittsburg  tests,  144 

Concrete  primer  formula, 218 

Constants  of  Pine  Oil,  18 

Pure  Gum  Turpentine,  19 

Co-operative  tests  of  Driers,  29-41 

Corn  Oil,  16 

Cottonseed  Oil,  15 

Damp-proofing  and  Waterproofing,    214 

Decay  of  Lithopone  paints,  124 

Decomposition  of  Paint,    122 

Driers,    Co-operative   tests   of,     29-41 

in    Boiled    Oil,     28 

Tests  of  Manganese,  Lead  and  Combination,  tables. 24-25 

Drying  Properties  of  Oil, 1,  26,  27 

Elasticity  and  Strength  of  Paint  Coating,     102 

Fence  tests  of  paints,    105 

Supervision    of,    112 

Film  sectioning,   87 

Film  testing  results,  table,    80 

Filometers, 74-79 


INDEX  261 

PAGE 

Formula  for  Blue  Paint  for  concrete  wall, 215 

Concrete  primer,  218 

Para  Red  Paint  for  concrete  wall, 217 

Formulas  of  Atlantic  City  fence  test, 108 

Tennessee  tests, 202,  204 

Washington  tests, 208,  211 

Fume  Pigments  Paints  in  Pittsburg  tests, 173 

General  results  of  Atlantic  City  tests, 128 

Gloss,  in  Atlantic  City  tests, 122 

Graphite,  . 66 

Grinding   Pigments,    87 

Green  paints  hi  Pittsburg  tests,    142 

Gums  as  moisture  resisters,     84 

Gypsum,    60 

Hailstorm,  effects  of  in  North  Dakota  tests, 185 

Hospital,    painting   practice,    254 

House  paint  tests  in  North  Dakota, 196 

Hydrocarbon  Oils,  16 

Imperviousness  of  paint  coating, 100 

Indian    Red,     62 

Inert  Pigments,  use  of, 99 

Inhibition  of  rust, 222 

Iodine  Values  of  Linseed  and  Mixed. Oils,  table, 8 

Iron   Oxide   Paints,    64 

Japan  driers  hi  tests  on  steel, 231 

Laboratory  tests,  panels  for,    149 

Lampblack, 66 

Laws  of  Paint  Making, 93 

Lime  action  on  paint,      214 

Linoxyn,    21 

Linseed  Oil,  boiled, ..*/.  2 

Chemical  action  of  pigments  upon, 91 

Table  of  Analyses  of  Various  Types  of, 7 

tests  of  Driers  with, ... 24,  25 

Lithopone,     .....*,.. ...V. 53 

paint  in  Pittsburg  tests,    . . . . . ... . ......;..... 136 

tests  at  Atlantic  City,      ..  .„„..........,'............... 124 

Lumbang  Oil, 12 

Magnesium  Silicate, , ; 55 

Manufacturing  Barytes,     55 

Blue  Lead,    47 


262  INDEX 

PAGE 

Manufacturing  Bone  Black, 66 

Paint  Pigments  42-68 

White  Lead,  42 

Menhaden  Oil,  12 

Constants  of,  table, 14 

Metallic  Brown,   62 

Microscope,  use  of  in  paint  laboratory,  86 

Microscopic  examination  of  paint,  preparation  for, 86 

measurements  of  paint  sections,  89 

Mineral  Black,  68 

Oils,  17 

Moisture  Absorption,  tests  in, 84 

experiments  with  various  Pigments,  83 

North  Dakota  Paints  tests, 182 

test    fence,     105 

report  of,   table,    193-195 

Ochre,    62 

Oil  and  Thinner  tests, 202 

Oil,    Corn,     16 

Cottonseed,   15 

Effects  of  Pigments  on,    90 

Linseed,     1 

Linseed,  Analyses  of  Various  Types  of,  table, 7 

Linseed,  Iodine  Values  of,  table,    8 

Linseed,  Tests  of  Driers  with, 24,  25 

Lumbang,    12 

Menhaden,    12 

Menhaden,  Constants  of,  table,    14 

Perilla,   21 

Pine, 18 

Rosin,     16 

Soya  Bean,  and  Driers,  table, 9 

Soya  Bean,    7 

Chemical   Characteristics  of,   table, 8 

Sunflower,    14 

Tung,    9 

Whale,    14 

Oils,  Constants  and  Characteristics  of,  1 

Drying   properties   of,    1,  26 

Hydrocarbon,    16 

In  Washington  paint  tests, 210 

Iodine  Value  of  Linseed  and  Mixed,  table, 8 

Mineral,     17 

Moisture  resistance  of,   84 

Oxygen  Absorbing   qualities, 21 


INDEX  263 

PAGE 

Oils,  Outline  of  tests  of  paints  on  concrete  walls, 216 

Oxygen  Absorption  in  Oils,  21 

Paint  Coating,  Adhesive  power  of, 104 

Elasticity  and  Strength  of, 102 

imperviousness    of,     100 

decomposition  of,    122 

films,  action  of  water  upon, ' 223 

permeability    of,     71 

Testing    machine,    74 

preparation  of,    70 

in  Hospitals,    254 

making,  Laws  of,    93 

Perry's   Principles  of,    100 

pigments, 42-69 

pigments,  properties  of,    42 

preparation  for  microscopic  examination  of, 86 

tests  at  North  Dakota  Experiment  Station, 105 

at  Washington 207-213 

supervisors    of,     113 

woods  used  on,  124,  135 

Painting  steel  plates  for  tests, 230 

Paints  for  cement  and  concrete  surfaces, 214 

composition  of  in  steel  test,    233 

hiding   power  of,    Ill 

sanitary    value    of,     252 

Panels  for  laboratory  tests,  149 

Para  Red  formula  for  concrete  wall,  217 

Paranitraniline  paints  in  Pittsburg  tests,  140 

Paranitraniline    Red,     64 

PariUa  Oil,  21 

Perry's  analogies  of  paint  and  concrete  manufacture, 99 

principles  of  Paint  Making, 100 

Petroleum  Spirits,  20 

Photomicrographs,    89,  165 

Pigment   contention,   the,     '. 105 

grinding,        . . . .'........... ;.....,....       87 

Pigments, .... . . .^ 42-69 

as  stimulators  of  rust, 223 

Chemical  action  of  upon  Linseed  Oil,  table,   91 

Effects  of  on  Oil, . . 90 

inert,  use  of,   '. 99 

moisture  experiments  with,  table, 1 83 

percentages  of  Oil  required  for  grinding, 68 

re-enforcing, ..*w . . 89 

report  of  results  of  steel  paint  tests,  236-251 

Water  resistance  of, 81 


264 


INDEX 


PAGE 

Pine  Oil,    18 

Pittsburg  fence  tests,    107 

Polar  Micro-Examinations  and  Photomicrographs,  89 

Primer  for  concrete,    218 

Properties  of  Paint  Pigments, 42 

Prussian    Blue,     66 

Red  Lead, 64 

Reductions  used  in  fence  tests, Ill 

Re-enforcing    Pigments,     89 

Results  of  new  test  at  Atlantic  City  test  fence  in  1910,  table, 178-181 

Pittsburg     tests,      135 

steel   test   plates,    232 

Rosin    Oil,    16 

Rust,  cause  of  in  steel  work,    220 

inhibition  of,    222 

stimulation    of,     223 

Sanitary  value  of  paints,   252 

wall  paints,  254 

Sienna,  62 

Silex, 60 

Silica,  60 

Silica  and  Barytes  Paints  in  Pittsburg  tests,  172 

Solvent  Naphtha, 20 

Soya  Bean  Oil  and  Driers,  table, 9 

Chemical  Characteristics  of,  table,  8 

Steel  Paint  test,  rating  report,  234 

reports  on  pigments  used,  236-251 

Steel  paint,  result  of  tests  at  Atlantic  City,  234,  235 

Steel,  preparation  of  for  paint  tests, 228 

water  contact  and  paint,  224 

Structural  steel  paint  tests,  220 

Sublimed  Blue  Lead,  47 

Sublimated  White  Lead, 46 

Suction  varnish,  215 

Sunflower  Oil,  14 

Constants  of,  table,  15 

Supervisors  of  paint  tests,  113 

Table  Analysis  of  Averages  in  Atlantic  City  Steel  Paint  test, 235,  236 

Analyses  of  Corn  Oil,    16 

Analyses  of  Derbloomed  Mineral  Paint  Oil,    18 

Analysis  of  Iron  Oxide  Pigments,    63 

Analyses  of  Oils  used  in  Washington  tests,   211 

Analyses  of  Petroleum  Spirits,    20 

Analyses  of  Rosin  Oil, 16 


INDEX  265 

PAGE 

Table  Analyses  of  various  types  of  Linseed  Oil,    7 

Analyses  of  wood  Turpentine,  19 

Atlantic  City  test  fence  formula, 108 

Chemical  Characteristics  of  Soya  Bean  Oil, 8 

Comparative  spreading  rates  of  White  Paint  in  Pittsburg  tests,  ....      148 

Composition  of  Blue  Lead,  49 

Composition  of  paints  in  Atlantic  City  Steel  test, 233 

Constants  of  Cottonseed  Oil,  table,   15 

Constants  of  Menhaden  Oil,    14 

Constants  of  Pine  Oil,    ". 18 

Constants  of  Sunflower  Oil, 15 

Constants   of  Whale  Oil, 14 

Co-operative    drying    tests,     32-41 

Excluding  tests  for  moisture  absorbed, 84 

Fineness  for   grinding   pigments,    87 

Formulas  in  Tennessee  tests,   204 

Iodine  Value  of  Linseed  Oil  and  Mixed  Oils, 84 

Moisture  experiments  with  various  pigments,  83 

Paint  section  measurements  under  microscope,   89 

Percentages  of  Oil  required  for  grinding  various  dry  pigments,    ....       68 

Permeability  of  Paints, 72 

Ratings  of  Atlantic  City  Steel  Paint  test, 234 

Report  of  North  Dakota  test  fence,  193-195 

Results  of  Atlantic  City  test  fence,  130,  131 

Results  of  new  tests  at  Atlantic  City  test  fence  in  1910, 178-181 

Results  of  second  annual  inspection  Atlantic  City  test  fence,  ....     133 

Results  of  second  annual  inspection  in  Pittsburg  tests, 145 

Showing  action  of  various  pigments  upon  Linseed  Oil, 91 

Soya  Bean  Oil  and  Driers,   9 

Tests  of  Linseed  Oil  and  Manganese,  Lead  and  Combination  Driers, .  24,  25 

Talcose,  55 

Tennessee    Paint    tests,     201-206 

Test  Fences  in  Paint  Experiments, 105 

at   Atlantic   City, 114-134 

at  Pittsburg, : 135-148 

at     Washington, . '. 207-213 

Cement    and    concrete,     214 

in     Tennessee, 201-206 

laboratory,     chalking,     • 149 

North   Dakota,    182 

of   Oil   and   Thinners,    202 

of  various  pigments  in  steel  paint,    236-251 

panel    sections    for, " 149 

Structural  steel  paints, 220 

Water    pigment,    '.I . •« 226 

Thinner,  Wood  Turpentine  as  a, 1 ......".... 202 

Tung    Oil, ....' 9 


266  INDEX 

PAGE 

Tung  Varnishes,  11 

Turpentine,  18 

Ultramarine  Blue, 66 

Umber, 62 

Varnishes  from  Tung  Oil, 11 

Vermilion,  American, 64 

Wall    paints,    252 

Wall  paper,  defects  of,    255 

Washington  Paint  tests,    207-213 

Water,  action  of  upon  paint  films,    223 

contact  with  steel  and  paint,   224 

resistance  of  Pigments, 81 

tests, 226 

Water-pigment  tests,      226 

Waterproofing  and   damp-proofing,     214 

Whale  Oil,    14 

White  Lead,  Basic  Carbonate, 42 

Basic  Sulphate,    46 

Mild    Process,     46 

Quick    Process,     45 

in  Pittsburg  tests,  139 

in  North  Dakota  tests,  190 

Paints,  checking  in  Pittsburg  tests, 172 

processes  of  manufacture  of,    43-46 

Whiting,    60 

Wood  Turpentine,  19 

experiments  with  as  a  thinner,    202 

Woods  used  in  paint  tests,  124,  135 

Zinc  Chromate,    64 

Zinc  Lead  White,    51 

Zinc  Oxide,  51 


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1960 

3Sep'64RR 


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LD  21-100m-9,'48(B399sl6)476 


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